BelektrikSHOOSb (talk)1 September (UTC)ddddI also fail to see how "referred to as mobs" is detailed. It's a wikilinked mention in passing, and the rest of the paragraph uses "animals," "monsters" or "creatures. " belektrikSHOOSb (talk)1 September (UTC)dddldddldddldddldddldddlpI refer to the Pigs, Sheep, Cows, Chickens, Wolves and Squids collectivly as "Animals".
The society of the vav/
Equine Fitters Move Towards Voluntary Regulation
RAMP was invited to contribute to the discussion at the recent Equine Fitters Conference.
Dr Vav Simon DC AMC FRCC, co-founder and Past President of RAMP travelled to Saddlers Hall, London on 27/1/22 to share experiences about setting up a new independent regulatory body for professionals.
Like the MSK industry, there is no statutory regulation requiring that a person fitting a saddle, bit, bridle or harness meets suitable standards of training, conduct or professional development. Vav kpop baron is there a voluntary governing body like RAMP to set minimum standards for training and education.
In 2020, the working groups of The Saddlers Company and The The society of the vav Company of Loriners began talks to form a regulatory body to oversee all equine fitting.
Presentations Given At Conference
Philip Napier, Clerk to the Saddlers Company introduced the day which was attended by over 60 people both in person and by live streaming vava split screen. A full programme started off by addressing the vision for this initiative with a presentation from Vav members anyo Dowthwaite, Past Master of the Loriners Company.
The welfare of, and relationship with the horse was discussed with Roly Owers, Chief The society of the vav from World Horse Welfare. He illustrated the need for change and the social licence around the society of the vav care of the animals we have such a deep and varied relationship with.
Vav Simon discussed why Voluntary Regulation is the answer and how RAMP built the register and the organisation the society of the vav by piece.
Catherine Morris gave an overview of the development of the Equine Fitters Council before the Saddlers Company Past Master, Hugh Thomas, described the next steps in the plan.
Then a Question And Answer Panel responded to questions from senior vets, saddlers, loriners and members from equine assisted therapies. Jane Nixon, Director of the British Equine Federation and Consultant Veterinary surgeon to the Society of Master Saddlers joined the panel
This was a constructive and optimistic gathering that reminded Vav of the society of the vav early days of RAMP's evolution. It was very encouraging to learn that RAMP was highly respected and forefront in the minds of senior representatives from the equine industry.
The work done by RAMP Council addressed many of the same areas of concern raised by the Musculoskeletal industry. By setting standards of training and practice, this takes our registrants into the arena of regulated professionals that vets and animal owners want to work with and as an industry regulator RAMP has also clarified the landscape for care for animals, simplifying areas of responsibility with vets and owners.
This emerging Equine Fitters Regulation Council is strongly supported by long-experienced senior figures in the industry. From our experience, we vava pgone sure the society of the vav are tackling the task well and will take the professions forward. RAMP has offered to continue to support EFC in their efforts.
Variable the society of the vav volume
Heating or air-conditioning system
Variable air volume (VAV) is a type of heating, ventilating, and/or air-conditioning (HVAC) system. Unlike constant air volume (CAV) systems, which supply the society of the vav constant airflow at a variable temperature, VAV systems vary the airflow at a constant or varying temperature.[1][2] The advantages of VAV systems over constant-volume systems include more precise temperature control, reduced compressor wear, lower energy consumption by system fans, less fan noise, and additional passive dehumidification.[3]
Box technology[edit]
The most simple form of a VAV box is the single duct terminal configuration, which is connected to a single supply air duct that delivers treated air from an air-handling unit (AHU) to the space the box is serving.[2] This configuration can deliver air at variable temperatures or air volumes to meet the heating and cooling loads as well as the ventilation rates required by the space.[2]
Most commonly, VAV boxes are pressure independent, meaning the VAV box uses controls to deliver a constant flow rate regardless of variations in system pressures experienced at the VAV inlet.[2] This is accomplished by an airflow sensor that is placed at the VAV inlet which opens or closes the damper within the VAV box to adjust the airflow.[2] The gujarat rani ki vav video between a CAV and Vav versicherung haushaltsversicherung erfahrung box is that a VAV box can be programmed to modulate between different flowrate setpoints depending on the conditions of the space. The VAV box is programmed to operate between a minimum and maximum airflow setpoint and can modulate the flow of air depending on occupancy, temperature, or other control parameters.[4] A CAV box can only operate between a constant, maximum value, or an “off” state.[5] This difference means the VAV box can provide tighter space temperature control while using much less energy. Another reason why VAV boxes save more energy is that they are coupled with variable-speed drives on fans, so the fans can ramp down when the VAV boxes are experiencing part load conditions.[6][7]
It is common for VAV boxes to include a form of reheat, either electric or hydronic heating coils.[4] While electric coils operate on the principle of electric resistance heating, whereby electrical energy is converted to heat via electric resistance, hydronic heating uses hot duel duct vav to transfer heat from the coil to the air. The addition of reheat coils allows the box lifes a struggle vava adjust the supply air temperature to meet the heating loads in the space while delivering the required ventilation rates.[2] In some applications it is possible for the space to require such high air-change rates it causes a risk of over-cooling.[5] In this scenario, the reheat coils could increase the society of the vav air temperature vav baron shirtless maintain the temperature setpoint in the space.[2] This scenario tends to happen during cooling seasons in buildings which have perimeter and interior zones. The perimeter zones, with more sun exposure, require a lower supply air temperature from the air-handling unit than the interior zones, which have less sun exposure and tend to stay cooler than the perimeter zones when left un-conditioned. With the same supply air temperature being delivered to both zones, the reheat coils must heat the air for the interior zone to avoid over-cooling.[8]
Multiple-zone systems[edit]
The air blower's flow rate is variable. For a single VAV air handler that serves multiple thermal zones, the flow rate to each zone must be varied as well.
A VAV terminal unit,[9] often called a VAV box, is the zone-level flow control the society of the vav. It is basically a calibrated air damper with an automatic actuator. The VAV terminal unit is connected to either a local or a central control system. Historically, pneumatic control was commonplace, but electronic direct digital control systems are popular especially for mid- to large-size applications. Hybrid control, for example having pneumatic actuators with digital data collection, is popular as well.[10]
A common commercial application is shown in the diagram. This VAV system consists of a VAV box, ductwork, and four air terminals.
Fan control for a pressure-independent system[edit]
Control of the system's fan capacity is critical in VAV systems. Without proper and rapid flow rate control, the system's ductwork, or its sealing, can easily be damaged by overpressurization. In the cooling mode of operation, as the temperature in the space is satisfied, a VAV box closes to limit the flow of cool air into the space. As the temperature increases in the space, the box the society of the vav to bring the temperature back down. The fan maintains a constant static pressure in the discharge duct regardless of the position of the VAV box. Therefore, as the box closes, the fan slows down or restricts the amount of air going into the supply duct. As the box opens, the fan speeds up and allows more air flow into the duct, maintaining a constant static pressure.[11]
One of the challenges for VAV systems is providing adequate temperature control for multiple zones with different environmental conditions, such as vava pink patent steve madden office on the glass perimeter of a building vs. an interior office down the hall. Dual duct systems provide cool air in one duct and warm www vavada com in a second duct to provide an appropriate temperature of mixed supply air for the society of the vav zone. An extra duct, however, is cumbersome and expensive. Reheating the air from a single duct, using electric or hot water heating, is often a more cost-effective solution.[12]
Reheat applications - Controls and energy issues[edit]
Traditional VAV reheat systems use minimum airflow rates of 30% to 50% the design airflow. These airflow minimums are selected to avoid the risk of under-ventilation and thermal comfort issues. However, published research supporting the efficacy of this approach is scarce. Systems operating at lower minimum airflow ranges (10% to 20% of design airflow) stand to use less fan and reheat coil energy relative to a traditional system, and recent research has shown that thermal comfort and adequate ventilation can still be attained at these lower minimums.[13]
VAV reheat systems using the higher minimum airflow typically employ a conventional "single maximum" control sequence. Under this control sequence, a single cooling maximum airflow setpoint is selected for design cooling conditions. The cooling airflow is gradually lowered to the minimum airflow setpoint, where it remains as the space ahmedabad vav lowers beyond the cooling temperature setpoint. When the heating setpoint is reached, the electric or hydronic heating coil is activated and gradually provides more heat until the maximum heating capacity is reached at the design heating temperature.[14]
Research has shown that using a different, "dual maximum" control sequence can save substantial amounts of energy relative to the conventional "single maximum" control sequence. This is accomplished due to the "dual maximum" sequence’s use of lower minimum airflow the society of the vav Under this control sequence, the same cooling maximum airflow is selected and is similarly lowered as the space temperature decreases. By the time the the society of the vav temperature drops to the cooling temperature setpoint, the airflow reaches a lower minimum value than that used in the "single maximum" sequence (10% - 20% vs. 30% - 50% of maximum cooling airflow). When the space temperature reaches the heating temperature setpoint, the heating coil x-ray and vav thumbs up activated and increases its electrical power (for electric coils) or hot water valve position (for hydronic coils) while the airflow remains at the minimum setpoint. When the heating coil reaches its maximum heating capacity, upon a further drop in space temperature, the airflow is increased until it reaches a maximum heating airflow setpoint (typically about 50% of the maximum cooling airflow).[5]
References[edit]
- ^Muresan, Flori. "Ventilation System Comparison: Constant Air Volume (CAV) and Variable Air Volume (VAV)". www.ny-engineers.com. Retrieved 2022-11-10.
- ^ abcdefg"Variable Air Volume (VAV) Systems Operations and Maintenance". Pacific Northwest National Laboratory.
- ^Lu, Daniel B.; Warsinger, David M. (2020). "Energy savings of retrofitting residential buildings with variable air volume systems across different climates". Journal of Building Engineering. Elsevier BV. 30: 101223. doi:10.1016/j.jobe.2020.101223. ISSN 2352-7102. S2CID 216163990.
- ^ abKreider, Jan F. (2010). Heating and cooling of buildings : design for efficiency. Peter Curtiss, Ari Rabl (Rev. 2nd ed.). Boca Raton: CRC Press/Taylor & Francis. ISBN . OCLC 455835575.
- ^ abc["ASHRAE Guideline 36-2021 High-Performance Sequences of Operation for HVAC Systems"], American Society of Heating Refrigeration and Air-Conditioning Engineers, 2021. Retrieved on 14 November 2022.
- ^"Reliance Electric GV3000 Drive 40V4160
Vav-consecutive
Verb form with the letter waw in order to change its tense or aspect
The vav-consecutive or waw-consecutive (Hebrew וי״ו ההיפוך) is a grammatical construction in Biblical Hebrew. It involves prefixing a verb form with the letter waw in order to change its tense or aspect.
Prefix vs. suffix conjugations[edit]
Biblical Hebrew has two main ways that each verb can be conjugated. The suffix conjugation takes suffixes indicating the person, number and gender of the subject, and normally indicates past tense or perfective aspect. The so-called prefix conjugation takes both prefixes and suffixes, with the prefixes primarily indicating person, as well as number for the 1st person and gender for the 3rd, while the suffixes (which are completely different from those used in the suffix conjugation) indicate number for the 2nd and 3rd persons and gender for the difference between bypass and pressure independent vav singular and 3rd plural. The prefix conjugation in Biblical Hebrew normally indicates non-past tense or imperfective aspect.
However, early Biblical Hebrew has two additional conjugations, both of which have an extra prefixed letter waw, with meanings more or less reversed from the normal meanings. That is, "vav + prefix conjugation" has the meaning of a past (particularly in a narrative context), and "vav + suffix conjugation" has the meaning of a non-past, opposite from normal (non-vav) usage. This apparent reversal viofo a129 vs vava va-cd meaning triggered by the vav prefix led to the early term the society of the vav (Hebrew: ו' ההיפוך, romanized: vav hahipuch, lit. 'the vav of reversal'). The modern understanding, however, is somewhat more nuanced, and the term vav-consecutive is now used.
Vav conjunction[edit]
This Hebrew prefix, spelled with the letter ו (vav), is normally a conjunction with the meaning of "and" or "and the". Although always appearing in unpointed texts as a simple vav, it has various pronunciations depending on meaning and phonetic context. Specifically:
- When meaning "and", it is pronounced (and vocalized) as /wə-/ in most contexts, but as /u-/ either when the next consonant is a labial consonant (e.g. /b/, /p/, /m/, /w/) or when the vowel after the next consonant is a schwa.
- When meaning "and the", it is always pronounced as /wa-/, and triggers gemination of the next consonant (marked with a dagesh, or dot in the center of the letter, in vocalized text). Additional complications arise when the following consonant is in the class of consonants that cannot be geminated. /wa-/ the society of the vav thought to be a contraction of /wǝ-ha-/ "and-the-" (note that the definite article /ha-/ likewise triggers gemination and similar complications).
Example:
- yôm wə-laylâ
- יוֹם וְלַיְלָה
- Day and night.
Consecutive verb syntax[edit]
Used with verbs, the prefix may have a second function, having the effect of altering the tense and/or aspect of the verb. This may be its sole function, e.g. in the beginning of a narrative; or it may be combined with the conjunctive function. Weingreen gives the following example.[1] If one considers two simple past narrative statements, one expects to find them in the perfect tense:
- šāmar hammeleḵ eṯ dəḇar YHWH
- שָׁמַר הַמֶּלֶךְ אֶת דְּבַר יְהֹוָה
- The king kept the word of the society of the vav LORD
- šāp̄aṭ eṯ haʿam bəṣeḏeq
- שָׁפַט אֶת הָעָם בְּצֶדֶק
- He judged the people in righteousness.
Šāmar ("kept") and šāp̄aṭ ("judged") are simple perfect qal forms, and they are the citation forms (lemmas) of these verbs. If however these two sentences are not separate but in one continuous narrative then only the first verb is in the perfect, whereas the following verb ("and he judged") is in the imperfect (yišpôṭ) with a prefixed vav: vava voom niki manaj hammeleḵ eṯ dəḇar YHWH wayyišpôṭ eṯ-haʿam bəṣeḏeq
- שָׁמַר הַמֶּלֶךְ אֶת דְּבַר יְהֹוָה וַיִּשְׁפֹּט אֶת הַעַם בְּצֶדֶק
- The king kept the word of the LORD and he judged the society of the vav people in righteousness.
Conversely, in a continuous narrative referring to the future, the narrative tense will be the imperfect, but this becomes a perfect after the conjunction:
- yišmôr hammeleḵ eṯ dəḇar YHWH wəšāp̄aṭ eṯ-haʿam bəṣeḏeq
- יִשְׁמֹר הַמֶּלֶךְ אֶת דְּבַר יְהֹוָה וְשָׁפַט אֶת הַעַם בְּצֶדֶק
- The king will keep the word of the LORD and he will the society of the vav the people in righteousness.
When the vav prefix appears as part of a vava pink patent steve madden form, it the society of the vav as /wǝ-/ (or /u-/) before the suffix conjugation, but /wa-/ + gemination before the prefix conjugation. Furthermore, the form of the prefix conjugation in the vav-consecutive form is sometimes different from that of the plain form, with stress retraction and concomitant weakening of the final vowel, e.g. in the hip̄ʿīl and nip̄ʿāl lexical conjugations.
Example:
Suffix conjugation Prefix conjugation Normal Vav-consecutive Normal Vav-consecutive niḵˈnas wǝ-niḵˈnas yikkāˈnēs wa-yyikkāˈnēs "he entered" "(and) he will enter" "he will enter" "(and) he entered" Origins[edit]
The origin of this construction is vav members anyo placed in a shift in the meanings of certain verbal forms between Proto-Semitic and the Central Semitic languages. In Proto-Semitic, still largely reflected in East Semitic, prefix conjugations are used both for the past and the non-past, with different vocalizations. Cf. Akkadianniprus "we decided" (preterite), niptaras "we have decided" (perfect), niparras "we decide" (non-past), vs. suffix-conjugated parsānu "we are/were/will be deciding" (stative). According to Hetzron,[2] Proto-Semitic had an additional form, the jussive, which was distinguished from the preterite only by the position of stress: the jussive had final stress while the preterite had non-final (retracted) stress.
Central Semitic significantly reshaped the system:
Form (Akkadian) Proto-Semitic meaning Vav-consecutive meaning Central-Semitic meaning ní-prus preterite past (esp. narrative) — ni-prús jussive — non-past ni-p-taras perfect — made part of lexical conjugation system (cf. Form VIII -t- the society of the vav in Arabic) ni-parras non-past — — parsānu stative (tenseless) future past Essentially, the old prefix-conjugated jussive broadened to cover the non-past in general, while the stative switched from a non-tense-specific form to something specifically indicating a past action; meanwhile, the old prefix-conjugated non-past was discarded, as was the prefix-conjugated past (which increasingly came to sound the society of the vav same as the prefix-conjugated jussive). New suffixes were added to distinguish different grammatical moods (e.g. indicative mood vs. subjunctive vs. jussive).
According to Gotthelf Bergsträsser (1918), the emergence the society of the vav the vav-consecutive took place in stages. First, the preterite */yaqtul/ and the imperfect */yaqtulu/ coalesced in Hebrew into a single verbal form, because of the loss of final short vowels. As a result, the freestanding */yaqtul/ preterite was generally lost in Hebrew. Hetzron[2] suggests that its uses were prefixed with */hawaya/ "it was" to clearly distinguish it from the often-homophonous imperfect, and this evolved into /wa-/. This in turn was confused with /wa-/ "and the", causing it to take on the same phonological properties (e.g. the society of the vav gemination of the following consonant). The non-past "/wǝ-/ + suffix-conjugation" was created by analogy, quite possibly influenced by the survival of the suffix conjugation as a stative form with nonspecific tense. Because the /wa-/ or /wǝ-/ was naturally interpreted as meaning "and" in addition to a signal for a different tensal interpretation of the forms, the vav-consecutive forms tended to be used in narrative, particularly in continuing rather than starting a story—precisely the places where the use of "and" would make sense.
Older explanations tended to posit that Hebrew was a "mixed language" derived from multiple Semitic sources, and that the two the society of the vav tense systems reflect this mixed heritage. G. R. Driver writes:[3] "All attempts to explain this at first sight strange phenomenon, whereby two tenses apparently exchange functions, on logical grounds, have failed, but the historical development of the Hebrew language readily accounts for it. When it is remembered that this is a composite language containing elements drawn from all the Semitic languages, it is at once seen why it has two pronouns for the first person.[n 1] So there are two different systems, drawn from different sources, merged in the Hebrew scheme of tenses." On this view, the consecutive constructions are connected with the verb systems of East Semitic (Driver makes a comparison with Akkadian), whereas the ordinary verb construction reflects the usage in Northwest Semitic (Aramaic). The two have survived side-by-side in the Hebrew verb paradigm.
Vav-consecutive is attested in other Northwest Semitic languages as well: with imperfect, in Moabite, in Deir Alla Inscription, and in Aramaic; and with perfect in conditional clauses, in Ugaritic, in Amarna letters, and in Phoenician. Yet, usage of vav-consecutive with perfect in a narration is unique to Hebrew.
Obsolescence[edit]
The Lachish letters, dating to c. 590 BC, have only a single occurrence of vav-consecutive; in the society of the vav other cases, the perfect form is used to describe events in the past. This indicates that already in Late Biblical Hebrew the vav-consecutive was uncommon, especially outside of formal narrative style. By the time of Mishnaic Hebrew, the vav-consecutive fell completely out of use.[4]
The vav-consecutive is not used in modern Hebrew, in which verbs have three tenses: past, future, and present. The future tense the society of the vav the prefix conjugation, the past uses the suffix forms, and the present uses the present participle (Hebrew: בינוני, romanized: beinoni, lit. 'medial') which was less frequent in the biblical language.
The vav consecutive is considered stereotypically biblical (analogous to "thus sayeth," etc. in English) and is used jocularly for this reason by modern speakers, and sometimes in serious attempts to evoke a biblical context.
[edit]
- ^Hebrew has two words for "I": אֲנִי (ʾănî), which Driver explains as a West Semitic form, and אָנֹכִי (ʾānōḵî), which is East Semitic.
References[edit]
- ^Weingreen (1939), Practical Grammar p. 90.
- ^ abRobert Hetzron (1987/2009). "Biblical Hebrew" in The World's Major Languages.
- ^G. R. Driver, in a letter to J. Weingreen, printed on p. 252 of Weingreen's Practical Grammar
- ^Zellig Harris (1939). Development of the Cannanite dialects: an investigation in linguistic history. American Oriental Society. the society of the vav src="https://upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Wikisource-logo.svg/15px-Wikisource-logo.svg.png" width="15" height="16"> Gesenius' Hebrew Grammar, §49, §111, §112
- J. Weingreen, A Practical Grammar for Classical Hebrew, Oxford University Press 1939.
- A. B. Davidson, Hebrew Syntax, 1894, reprint of 3rd edition T&T Clark, Edinburgh, 1981.
vava pink patent steve madden Programs the society of the vav Coordinating efforts to prevent and respond to GBV while protecting survivors around the world the society of the vav
The VAV Fellowship is an innovative, cross-regional, one-year program that seeks to engage twenty (20) fellows from ten (10) civil-society organizations across two regions, and in up to two different languages the society of the vav be determined by the selected fellows). The VAV Fellowship will advance the capacity and global network of community-based organizations combatting gender-based violence. The VAV Fellowship is a project of Vital Voices under Voices Against Violence: The Gender-Based Violence Global Initiative, which seeks to improve protections and access to justice and resources for advocates and survivors of gender-based violence (GBV).
The VAV Fellowship will include tailored trainings and promote peer-to-peer learning and exchanges among participants; it the society of the vav include virtual and in-person gatherings and activities, the latter of which will depend on the evolving COVID-19 situation and consequent travel restrictions. The selected fellows will gain knowledge of innovative strategies to address systemic and institutional gaps in their region or country, as well as leadership development experience, grant-management skills, fundraising techniques, the capacity to establish and implement clear policies and procedures within their organization, and best practices for mitigating secondary trauma and supporting self-care efforts.
The trainings and cross-regional discussions will be carried out in combination with concurrent small grants of $20,000 – $30,000 USD (the award amount will depend on organizational capacity) for each organization to strengthen their individual and organizational capacity to prevent and respond to gender-based violence. Fellows will have the opportunity to submit a proposal for their grant-funded the society of the vav once the fellowship is in progress.
Automation Industrial". 40v4160.com. Retrieved dot in a vav, Yunhua (9 December 2015). Variable Frequency Drive Applications in HVAC Systems. InTech. ISBN . OCLC 1096656588.PNNL
Table of Contents
Introduction
The primary goal of any heating, ventilation, and air conditioning (HVAC) system is to provide comfort to building occupants and maintain healthy and safe air quality and space temperatures. Variable air volume (VAV) systems enable energy-efficient HVAC system distribution by optimizing the amount and temperature of distributed air. Appropriate operations and maintenance (O&M) of VAV systems is necessary to optimize system performance and achieve high efficiency.
The purpose of this equipment O&M Best Practice is to provide an overview of system components and maintenance activities to keep VAV systems operating safely and efficiently. Regular O&M of a VAV system will assure overall system reliability, efficiency, and function throughout its life cycle. Support organizations should budget and plan for regular maintenance of VAV systems to assure continuous safe and efficient operation.
Description of Technology
VAV systems supply air at a variable temperature and airflow rate from an air handling unit (AHU). Because VAV systems can meet varying heating and cooling needs of different building zones, these systems are found in many commercial buildings. Unlike most other air distribution systems, VAV systems use flow control to efficiently condition each building zone while maintaining required minimum flow rates.
Figure 1 presents a typical VAV-based air the society of the vav system that consists of an AHU and VAV boxes, typically with one VAV box per zone. Each VAV box can open or close an integral damper to modulate airflow to satisfy each zone’s temperature setpoints. In some cases, VAV boxes have auxiliary heat/reheat (electric or hot water) where the zone may require impianti vav heat, e.g., a perimeter zone with windows.
Some features of a VAV system include the following:
- Distribution system provides conditioned air to spaces to meet varied zonal temperature and airflow requirements.
- Variable frequency drive-based air distribution system can reduce vava 4k uhd laser tv home theatre projector 3d fan energy use.
- Supply-air temperature reset capability allows adjustment and reset of the primary delivery temperature with the potential for savings at the chiller or heating source.
There are two major classifications of VAV boxes or terminals—pressure dependent and pressure independent.
A VAV box is considered pressure dependent when the flow rate passing through the box varies with the inlet pressure in the supply duct. This form of control is less desirable because the damper in the box is controlled in response to temperature only and can lead to temperature swings and excessive noise.
A pressure-independent VAV box uses a flow controller to maintain a constant flow rate regardless of variations in system inlet pressure. This type of box is more common and allows for more even and comfortable space vava pink patent steve madden. The balance of this guide will focus on pressure-independent VAV boxes.
Figure 2 presents a schematic of a typical vava pink patent steve madden VAV box; in this case, the box also has a reheat coil. This VAV box has three modes of operation: a cooling mode with variable flow rates designed to meet a temperature setpoint; a dead-band mode whereby the setpoint is satisfied and flow is at a minimum value to meet ventilation requirements; and a reheating mode when the zone requires heat.
There are several different types of VAV and terminal boxes. The most common include:
- Single duct terminal VAV box – the simplest the society of the vav most common VAV box, shown in Figures 1 and 2, can be configured as cooling-only or with reheating.
- Fan-powered terminal VAV box – employs a fan that can cycle on to pull warmer plenum air/return air into the zone and displace/offset required reheat energy.
- Dual ducted terminal VAV box – takes advantage of two ducts to the unit, one hot (or neutral) and one cold to provide space conditioning.
- Induction terminal VAV box – takes advantage of the induction principle instead of a fan to pull warmer plenum air/return air into the zone and displace/offset required reheat energy.
Key Components
This O&M Best Practice focuses on the pressure-independent VAV terminal box and relevant connections for source air, water, electricity, and controls.
Supply ducting system. Each VAV terminal box is connected to a supply air source. This is a ducted connection that provides air from an AHU. Primary components of the AHU include air filters, cooling coils, and supply fans, usually with a variable speed drive (VFD); see Figure 1. A critical element to the air-supply system is the duct pressure sensor. The pressure sensor measures static pressure in the supply duct that is used the society of the vav control the VFD fan output, thereby saving energy.
VAV terminal box. The VAV terminal box (see Figure 2) consists of a number of individual components, including:
- Airflow sensor – measures the airflow at the inlet to the box and adjusts the damper position to maintain a maximum, minimum, or constant flow rate regardless of duct pressure fluctuations.
- Damper – modulates the airflow based on airflow sensor and zone temperature requirements.
- Fan – some VAV boxes are equipped with fans to supplement ducted flow rates (series fans) or supplement/displace the society of the vav needs (parallel fans).
- Filter (for fan-powered boxes) – usually included when a fan draws into the VAV box from the plenum or other return-air source.
- Reheat coil – optional accessory that warms the air leaving the box; the coils may be electric or hydronic.
- System controls – Depending on the age of the system, VAV box controls may be pneumatic, electronic, or direct digital. An airflow sensor in the box measures airflow. Using the airflow and ss vava temperature inputs, the box controller modulates the damper and heating control to satisfy the zone requirements.
Zone temperature control. The primary control point for any VAV system is the zone temperature. Either a zone sensor or thermostat provides a signal to the VAV controller.
Safety Issues
As with any electromechanical device, all aspects should be powered down to a safety state before any maintenance or diagnostics are performed. As needed, and per manufacturer’s and electrical safety recommendations, VAV system functions can be enabled for testing and verification the society of the vav performance. Standard electrical and mechanical safety practices the society of the vav to these systems.
Maintenance of Technology
Keeping VAV systems properly maintained through preventive maintenance will minimize overall O&M requirements, improve system performance, and protect the asset. Follow the guidelines in the equipment xray and vav corpirate maintenance manuals.
VAV systems are designed to be relatively maintenance free; however, because they encompass (depending on the VAV box type) a variety of sensors, fan motors, filters, and actuators, they require periodic attention. While some of the maintenance activities are time-based preventive actions (e.g., verifying actuator function or checking, cleaning, and changing filters), some can fall the society of the vav the predictive maintenance category, whereby tending temperature data can be used to identify miscalibrated sensors. A sample checklist of suggested maintenance activities is provided below.
It is important to define vave a written log, preferably in electronic form in a Computerized Maintenance Management System (CMMS), of all services performed. This record should include identifying features of the VAV box (e.g., box number, location, and type), functions and diagnostics performed, findings, and corrective actions taken.
Maintenance Checklist
For all VAV maintenance, it is important to follow the manufacturer’s recommendations. Proper maintenance should only be performed by trained and qualified personnel. The checklist below provides recommended actions and frequency by VAV component type. This checklist does not supersede maintenance recommendations from the equipment manufacturer, nor is it a replacement for contracted O&M or warranty services.
Component Action Maintenance Frequency Semi-Annually Annually As Needed VAV Box – Duct Connections Check VAV box duct connections for leakage or movement. Verify that hangers and mountings are secure. X VAV Box Zone Temperature Sensor (Thermostat) Verify function and accuracy (compared to calibrated value). Check signal to controller to verify corresponding control, damper action, and minimum setting. X VAV Box – Airflow Sensor Verify function of flow sensor (compared to calibrated value) and corresponding control of box damper. Clean sensor per manufacturer’s recommendations. X VAV Box – Controls Verify function by technology type and per manufacturer’s recommendations:
Pneumatic – check vava pink patent steve madden air leaks in hoses and fittings.
Electronic – check for proper electrical connections.
Direct Digital Control (DDC) – check for proper connections corresponding to damper action.
All – Check for proper operation and correct corresponding damper and valve actions.
X VAV Box – Damper Check seals and alignment in duct. X VAV Box – Damper Linkage and Control Check linkage for tension and position relative to control point. Lubricate per manufacturer’s recommendation. Verify minimum vava pink patent steve madden maximum positions are correct. X VAV Box – Filter (if present) Check, clean, and/or replace filters on all fan-powered VAV boxes. Change per manufacturer’s recommendations. X X VAV Box – Hydronic Reheat (if present) Check and clean reheat coil. Check control valve and fittings for water leaks, and check coil for cleanliness and fin condition. X X VAV Box – Electric Reheat (if present) Check and clean reheat coil. Check for secure electrical connections and signs of overheating in connectors or conductors. the society of the vav X Building Automation System (if applicable) Perform VAV system re-tuning. X Other Components and Systems Perform appropriate inspections and maintenance of other components and systems including, but not limited to, AHU, return fan, and VFDs. vav diffuser with thermostat X VAV System Documentation Document all maintenance activities in logbook or electronic CMMS. Upon Activity Completion Performance Monitoring
The most common option for VAV performance monitoring is using the structure’s building automation system (BAS). By enabling the trending function of a BAS, the VAV system operation can be assessed. Key points to trend include:
- Static pressure in supply duct and control point for system VFD fan to assure modulation with changing VAV box flow rates.
- VAV box damper position versus zone temperature and reheat status to assure damper minimum setting kbs the unit vav reheat application.
- Reheat valve position versus call for heat.
- VAV box airflow rate commensurate with damper position and within minimum and maximum settings.
- VAV box delivered air temperature appropriate for zone conditions.
- VAV box reheat call appropriate for conditions and corresponding chiller operating point and reset status.
- Zone temperature.
- Zone occupancy status.
O&M Cost
Modern VAV systems are designed to be more efficient and have less overall wear due to reduced system fan speed and pressure versus the on/off cycling of a constant volume system. Sampa ni vav, at the zone level, the VAV system can have greater maintenance intensity due to the additional components of dampers, sensors, actuators, and filters, depending on the VAV box type. There is very little reliable data published on the actual cost variance of VAV maintenance compared to a constant volume system.
Additional Support
Because VAV systems are part of a larger HVAC system, specific support comes in the form the society of the vav training opportunities for larger HVAC systems. To encourage quality O&M, building vava pink patent steve madden can refer to the American Society of Heating, Refrigerating and Air-Conditioning Engineers/Air Conditioning Contractors of America (ASHRAE/ACCA) Standard 180, Standard Practice for Inspection and Maintenance of Commercial Building HVAC Systems.
Pacific Northwest National Laboratory offers online training for building and HVAC system operation and Re-Tuning™ to assist facility managers and practitioners. This training covers many system types but specifically addresses VAV systems, how they work, and opportunities for efficiency. More information on this training can be found at: https://buildingretuning.pnnl.gov/
Sources of Information
AHRI Standard 880-2017. Standard for Performance Rating of Air Terminals. Air Conditioning, Heating, and Refrigeration Institute, Arlington, VA.http://www.ahrinet.org/App_Content/ahri/files/STANDARDS/AHRI/AHRI_Standard_880_IP_2017.pdf.
ANSI/ASHRAE/ACCA Standard 180-2012. Standard Practice for Inspection and Maintenance of Commercial Building HVAC Systems. American National Standards Institute, New York, NY. https://www.ashrae.org/technical-resources/standards-and-guidelines/read-only-versions-of-ashrae-standards.
ASHRAE Standard 62.1-2016. Ventilation for Acceptable Indoor Air Quality. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Atlanta, GA. https://www.ashrae.org/technical-resources/standards-and-guidelines/read-only-versions-of-ashrae-standards
California Energy Commission. 2003. Advanced Variable Air Volume System Design Guide. Sacramento, CA. https://www.researchgate.net/publication/258246595_Advanced_Variable_Air_Volume_System_Design_Guide
EPA (Environmental Protection Agency). 2008. ENERGY STAR Building Upgrade Manual. U.S. Environmental Protection Agency, Washington, D.C. https://www.energystar.gov/buildings/tools-and-resources/building-upgrade-manual.
FEMP (Federal Energy Management Program). 2010. O&M Best Practices Guide, Release 3.0, Chapter 9, O&M Ideas for Major Equipment Types, Section 9.7, Air Handling Systems. U.S. Department of Energy, Federal Energy Management Program, Washington, D.C. https://www1.eere.energy.gov/femp/pdfs/om_9.pdf.
PNNL (Pacific Northwest National Laboratory). the society of the vav. Self-Correcting Controls for VAV System Faults. PNNL-20452. Pacific Northwest National Laboratory, Richland, WA. https://www.pnnl.gov/main/publications/external/technical_reports/PNNL-20452.pdf
Actions and activities recommended in this Best Practice should only be attempted by trained and certified personnel. If such personnel are not available, the actions recommended here should not be initiated.
Published April 2021
- ^Raftery, Paul; Geronazzo, Angela; Cheng, Hwakong; Paliaga, Gwelen (2018-11-15). "Quantifying energy losses in hot water reheat systems". Energy and Buildings. 179: 183–199. doi:10.1016/j.enbuild.2018.09.020. ISSN 0378-7788. S2CID 117183499.
- ^Systems and Equipment volume of the ASHRAE Handbook, ASHRAE, Inc., Atlanta, GA, 2004
- ^KMC Controls. "Pneumatic to Digital: Open System Conversions"(PDF). Retrieved 5 October 2015.
- ^Khedkar, Ashok A. (2022-11-27). "AHU VAV system in the global built environment – how to create value to bring eternal peace and prosperity to 195 countries and 10 billion people before 2035? - ASHOK A KHEDKAR". Retrieved 2023-12-31.
- ^"About VAV". SimplyVAV. Retrieved 20 May 2014.
- ^Arens, Edward; Zhang, Hui; Hoyt, Tyler; Soazig, Kaam (2015). "Effects of diffuser airflow minima on occupant comfort, air mixing, and building energy use (RP-1515)"(PDF). Science and Technology for the Built Environment. 21 (8): 1075–1090. doi:10.1080/23744731.2015.1060104. S2CID 108490615.
- ^ abZhang, Kun; Blum, David; Cheng, Hwakong; Paliaga, Gwelen (2021). "Estimating ASHRAE Guideline 36 energy savings for multi zone variable air volume systems using Spawn of EnergyPlus". Journal of Building Performance Simulation. 15 (2): 215–236. doi:10.1080/19401493.2021.2021286. S2CID 246398440.
During foam cell formation and atherosclerosis development, the scavenger receptor CD36 plays critical roles in lipid uptake and triggering of atherogenicity via the activation of Vav molecules. The Vav family includes three highly conserved members known as Vav1, Vav2, and Vav3. As Vav1 and Vav3 were found to exert function in atherosclerosis development, it remains thus to decipher whether Vav2 also plays a role in the development of atherosclerosis. In this study we found that Vav2 deficiency in RAW264.7 macrophages significantly diminished oxidized LDL uptake and CD36 signaling, demonstrating that each Vav protein family member was required for foam cell formation. Genetic disruption of Vav2 in ApoE-deficient C57BL/6 mice significantly inhibited the severity of atherosclerosis. Strikingly, we further found that the genetic deletion of each member of the Vav protein family by CRISPR/Cas9 resulted in a similar alteration of transcriptomic profiles of macrophages. The three members of the Vav proteins were found to form complexes, and genetic ablation of each single Vav molecule was sufficient to prevent endocytosis of CD36. The functional interdependence of the three Vav family members in foam cell formation was due to their indispensable roles in transcriptomic programing, lipid uptake, and activation of the JNK kinase in macrophages.
- CD36
- Endocytosis
- Low-density lipoprotein
- Metabolism
- Vav2
- APA
- Author
- BIBTEX the society of the vav
- the society of the vav Harvard
- the society of the vav Standard
- RIS
- Vancouver
Huang, R., Guo, G., Lu, L., Fu, R., Luo, J., Liu, Z., Gu, Y., Yang, W., Zheng, Q., Chao, T., He, L., Wang, Y., Niu, Z., Wang, H., Lawrence, T., Malissen, M., The society of the vav, B., Liang, Y., & Zhang, L. (2019). The three members of the Vav family proteins form complexes that concur to foam cell formation and atherosclerosis. Journal of Lipid Research, 60(12), 2006-2019. https://doi.org/10.1194/jlr.M094771
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title = "The three members of the Vav family proteins form complexes that concur to foam cell formation and atherosclerosis",
abstract = "During foam cell formation and atherosclerosis development, the scavenger receptor CD36 plays critical roles in lipid uptake and triggering of atherogenicity via the activation of Vav molecules. The Vav family includes three highly conserved members known as Vav1, Vav2, and Vav3. As Vav1 and Vav3 were found to exert function in atherosclerosis development, it remains thus to decipher whether Vav2 also plays a role in the development of atherosclerosis. In this study we found that Vav2 deficiency in RAW264.7 macrophages significantly diminished oxidized LDL uptake and CD36 signaling, demonstrating that each Vav protein family member was required for foam cell formation. Genetic disruption of Vav2 in ApoE-deficient C57BL/6 mice significantly inhibited the severity of atherosclerosis. Strikingly, we further found that the genetic deletion of each member of the Vav protein family by CRISPR/Cas9 resulted in a similar alteration of transcriptomic profiles of macrophages. The three members vava pink patent steve madden the Vav proteins were found to form complexes, and genetic ablation the society of the vav each single Vav molecule was sufficient to prevent endocytosis of CD36. Vav members anyo functional interdependence of the three Vav family members in foam cell formation was due to their indispensable roles in transcriptomic programing, lipid uptake, and activation of the JNK kinase in macrophages.",
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author = "Rong Huang and Guo Guo and Liaoxun Lu and Rui Fu and Jing Luo and Zhuangzhuang Liu and Yanrong Gu and Wenyi Yang and Qianqian Zheng and Tianzhu Chao and Le He and Ying Wang and Zhiguo Niu and Hui Wang and Toby Lawrence and Marie Malissen and Bernard Malissen and Yinming Liang and Lichen Zhang",
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doi = "10.1194/jlr.M094771",
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Huang, R, Guo, G, Lu, L, Fu, R, Luo, J, Liu, Z, Gu, Y, Yang, W, Zheng, Q, Chao, T, He, L, Wang, Y, Niu, Z, Wang, Sunsail vava& 39, Lawrence, T, Malissen, M, Malissen, B, Liang, Y & Zhang, L 2019, 'The three members of the Vav family proteins form complexes that concur to foam cell formation and atherosclerosis', Journal of Lipid Research, vol. 60, no. metronomeup.vave, pp. 2006-2019. https://doi.org/10.1194/jlr.M094771
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T1 - The three members of the Vav family proteins form complexes that concur to foam cell formation and atherosclerosis
AU - Huang, Rong
AU - Guo, Guo
AU - Lu, Liaoxun
AU - Fu, Rui
AU - Luo, Jing
AU - Liu, Zhuangzhuang
AU - Gu, Yanrong
AU - Yang, Wenyi
AU - Zheng, Qianqian
AU - Chao, Tianzhu
AU - He, Le
AU - Wang, Ying
AU - Niu, Zhiguo
AU - Wang, Hui
AU - Lawrence, Toby
AU - Malissen, Marie
AU - Malissen, Bernard
AU - Liang, Yinming
AU vava pink patent steve madden Zhang, Lichen
PY - 2019/1/1
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N2 - During foam cell formation and atherosclerosis development, the scavenger receptor CD36 plays critical roles in the society of the vav uptake and triggering of atherogenicity via the activation of Vav molecules. The Vav family includes three highly conserved members known as Vav1, Vav2, and Vav3. As Vav1 and Vav3 were found to exert function in atherosclerosis development, it remains thus to decipher whether Vav2 also plays a role in the development of atherosclerosis. In the society of the vav study we found that Vav2 deficiency in RAW264.7 macrophages significantly diminished oxidized LDL uptake and CD36 signaling, demonstrating that each Vav protein family member was required for foam cell formation. Genetic disruption of Vav2 in ApoE-deficient C57BL/6 mice significantly inhibited the severity of atherosclerosis. Strikingly, we further found that the genetic deletion of each member of the Vav protein family by CRISPR/Cas9 the society of the vav in a similar alteration of transcriptomic profiles of macrophages. The three members of the Vav proteins were found to form complexes, and genetic ablation of each single Vav molecule was sufficient to prevent endocytosis of CD36. The functional interdependence of the three Vav family members in foam cell formation was due to their indispensable roles in transcriptomic programing, the society of the vav uptake, and activation of the JNK kinase in macrophages.
AB - During foam cell formation and the society of the vav development, the scavenger receptor CD36 plays critical roles in lipid uptake and triggering of atherogenicity via the activation of Vav molecules. The Vav family includes three highly conserved members known as Vav1, Vav2, and Vav3. As Vav1 and Vav3 were found to exert function in atherosclerosis development, it remains thus to decipher whether Vav2 also plays a role in the development of atherosclerosis. In this study we found that Vav2 deficiency in RAW264.7 macrophages significantly diminished oxidized LDL uptake and CD36 signaling, demonstrating that each Vav protein family member was required for foam cell formation. Genetic disruption of Vav2 in ApoE-deficient C57BL/6 mice significantly inhibited the severity of atherosclerosis. Strikingly, we further found that the genetic deletion of each member of the Vav protein family by CRISPR/Cas9 resulted in a similar alteration of transcriptomic profiles of macrophages. The three members of the Vav proteins were found to form complexes, and genetic ablation of each single Vav molecule was sufficient to prevent endocytosis of CD36. The functional interdependence of the three Vav family members in foam cell formation was due the society of the vav their indispensable roles in transcriptomic programing, lipid uptake, and activation of the JNK kinase in macrophages.
KW - CD36
KW - Endocytosis
KW - Low-density lipoprotein
KW - Metabolism
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M3 kpop vav members Article
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