10541

BN-97-17-2

New Threshold Exhaust Flow Rates for Capture and Containment of Cooking Effluent

Richard T. Swierczyna Associate Member ASH RAE

Vernon A. Smith, J.D., P.E. Associate Member ASH RAE

Ferdinand P. Schmid

ABSTRACT

This paper presents results of applying the capture and containment test procedures in ASTM Fl 704-96, Standard Test Method for Performance of Commercial Kitchen Ventila­tion Systems, to determine the threshold capture and contain­ment exhaust flow rates for a number of cooking appliances and two types of kitchen exhaust hoods. It presents new data showing threshold capture and containment values for several common cooking appliances and compares them to both the International Mechanical Code values and test values based on Underwriter Laboratories Standard 710, Standard for Exhaust Hoods for Commercial Cooking Equipment.

BACKGROUND

Mechanical building code requirements for capture and containment (C&C) of cooking effluent originated as a fire safety issue. Grease particles in the cooking effluent can create a fire hazard if permitted to accumulate on kitchen surfaces. Exhausting the entire cooking plume avoids this problem as well as removing part of the heat generated by the appliance.

ANSI/NFP A Standard 96, Vapor Removal from Cooking Equipment. originated as a specification standard that is refer­enced by the model codes published by Building Officials & Code Administrators International (BOCA), International Conference of Building Officials (ICBO), and Southern Building Code Congress International (SBCCI). These orga­nizations determined the exhaust flow rates of kitchen hoods primarily by their physical dimensions, except for ICBO, which also classified cooking operations. Values selected for minimum exhaust rates were based primarily on field experi­ence.

UL 710, Stand<!rd for Exhaust Hoods for Commercial Cooking Equipment, was the first widely accepted standard to incorporate performance-based criteria to evaluate capture and containment during a cooking operation. In addition UL

710 has requirements for evaluating hood materials, operating temperatures, filter integrity , and fire suppression systems. It is widely accepted by code officials in lieu of code specifica­tions.

Historically, all codes and standards related to kitchen exhaust hoods were written for fire safety considerations. Kitchen indoor air quality was not addressed. Indoor air qual­ity has recently become another concern that can be partially addressed by evaluating capture and containment.

C&C Fundamentals

There are three commonly applied visual techniques for evaluating capture and containment: (1) observing cooking effluent, (2) seeding with theater smoke, and (3) seeding with neutrally buoyant, helium-filled soap bubbles. The first tech­nique relies on smoke, water vapor, and particles generated by the cooking process to trace the cooking plume and to permit human observers to decide if the exhaust flow rate is sufficient to fully capture and contain the cooking effluent. If the cook­ing plume does not generate sufficient particles to permit easy observation, the exhaust flow may be seeded artificially with smoke or soap bubbles. Seeding with smoke or soap bubbles is also a good technique while the appliance is in a ready-to­cook condition and only a thermal plume is being generated.

Recent research has applied the schlieren optical effect to thermal and cooking plume evaluation. The schlieren effect is based on the refraction of light as it passes through fluid layers with differing densities . In the case of cooking, the variation in density within the thermal plume and the air surrounding the cooking appliance causes refraction in a light beam. By using a special optical system; the entire thermal plume can be visu­alized as a two-dimensional video image that shows changes in the plume over time. The research reported in this paper uses a custom-designed, large-scale, focusing schlieren flow visualization system (Schmid et al. 1997).

Richard T. Swierczyna is laboratory operations manager at Architectural Energy Corporation, Wood Dale Ill. Vernon A. Smith is senior engi­neer/project manager and Ferdinand P. Schmid is a staff engineer at the Architectural Energy Corporation, Boulder, Colo.

THIS PREPRINT IS FOR DISCUSSION PURPOSES ONLY, FOR INCLUSION IN ASHRAE TRANSACTIONS 1997, V. 103, Pt. 2. Not to be reprinted in whole or in part without written permission of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. , 1791 Tu lie Circle, NE, Atlanta, GA 30329. Opinions, findings , conclusions, or recommendations expressed in this paper are those of the author(s) and do not necessarily r fleet the views of ASH RAE. Written questions and comments regarding this paper should be received at ASH RAE no later than July 18, 1997.

Criteria for Commercial Kitchen Ventilation in Building Codes

Historical specification of minimum exhaust flow rates (e.g., 100-150 cfm per square foot of hood area of hood tested would yield 2000-3000 cfm net or 400~600 cfin per Linear foot, '. or 508-762 Lis per square meter of hood area of hood tested would yield 944-1416 Lis net or 619-929 Lis per linear_meter of hood) by the model code organizations was conservative. Minimum values were based primarily on field experien~e since there were few performance-based data available. The flow rate scheme adopted by the model code organizations provides a large built-in factor of safety.

and miscellaneous heat sources not under the hood(s), and a means of providing make-up air, which may include make-up through the hood as well as th~ HV AC system. Ventilation

. system performance includes the evaluation of capture and containment of products from, cooking operations and the 'effect of heat gai11ed by the space which impacts human comfort and equipment operation, over exhaust flow rates ranging from the threshold of minimum capture to maximum capacity or code value. This paper addresses only the visual capture and containment testing under ASTM F 1704-96.

Test Faciiity

ASTM 1704-96 requires that the test facility be essen-However, the three major model code organizations had slightly different requirements for different cooking apgli­ances and types of hoods. There has been considerable indus­try qisc,ussio1,1 in ·.tl-ie fo~t ten years rega.rding the; p110blems encountered .bv hood and aonliance manufacturers and la!'"ge . .. ,_ .. >~- . . • _.

commercial '. restaurant ..:;qmpal)i"!s in attempting,!to meet the code f?-quinnn,ants in differeJJt jurisdh.:tions with the,,same avolhmce and .hood combination. '. , . . : ! . : ; ",

' .... t_ially.airtigh~,:~o minirp.ize air Je,akage through the test facility walls, floor, and roof and to ensure that the exhaust rate equals the supply rate. The exhaust hood under test is connected to an exhaust duct and fan. The exhaust fan is controlled by a vari­able-speed drive to provide operation over a wiC:e range of exhaust rates. A complementary make-up (supply) air fan is c.nntrnllecl tn h::ihmc.e the exhm1.~t rnte. therehv m::iint::iininP' :i

rn. 199t\the three major model code,0rganizations, under a n:ew ~x1tity form.ed by, them and cillt~ the International1Code Oouncil; held, public· meetings i regarding development of a cpnsolidated cope. The ·aotual code requireme:its ad0pted under the sJev.: 1996 InternationalMechani0a W.ode (IMC ai'e very 1 ~ imilar tO?. those under. tb:i ·most recentTv,ersion of the Unifrm,i1 Mecb,anical C0de. It.is anticipated that 1 tl.1.~,1MC will be. ad pted by the three regic;-na\ model code e.rgan izations over the next several years. Local•jurisdictions wi Lu1ost likt;ly adopt it during their subsequent code revision cycles.

Perfortnante~aased Criteria . ,

Previous 1ntAel codes liave provi ded 1exceptions to the mancla~ed exhaust flow rates. One e:ccept iqu is based on ratings establishednmder a recognized· est pro~ocol, such as Underwriters Labcxrat0ry Standard .1!.JL 710; Exhaust Hoods for OommerciaI Cooking1Equipment. UL .7 liO covers numen ous· safety features of, exhaust hoods ih ·addition to a test to ,determine captur.e and containment un!ler.cooking conditions.

Recent research conducted at two commercial cooking ventilation laboratories (Gordon et al 1994; Smith et al 199,5) resulted in the adoption of visual criteria for identifying the minimum threshold of capture and containment under cook~ ing conditions, as well as idle conditions, in ASTM 1704-96·. The standard requires that any observed spillage moving beyond three inches (760 mm) from the hood face be construed as having escaped from the hood, even if it appears to have been drawn back into the hood.

TESTING PROCEDURE

The overall scope of ASTM 1704-96 covers the overall I

performance evaluation of exhaust !ioods with commercial cooking appliances and associated replacement air configura­tion. Such systems include one or more exhaust hoods, one or more cooking appliances under the hood(s}, other applianl)es

2

negligible static pressure difference between the inside and outside of the test room. When the room is balanced, the exhaust flow rate equals the make-up airflow rate.

Because of potential problems with measurement in the hot, possibly grease-laden exhaust airstream, exhaust airflow rate is dete-rmined by measuring the make-up airflow rate on the supply side. Make-up air is supplied to the laboratory through a supply air system that includes an airflow measure­ment chamber and heating' and cooling coils. The supply air temperature is maintained in the range 75-78°F (23.9-25 .6°C) .

Two visual minimum capture and containment airflow rates are established with the appliance idling (i.e., ready-to­cook ;node) and one with the appliance cooking food under full-load conditions.

Exhaust Hoods

The exhaust~.~ply can9py hood ~,sed for this investigation is UL Listed at 1300 cfm (614L/s) for cooking operations with maximum appliance surface temperatures of 600°F (316°C). It. is 5 feet wide by 4 feet deep by 2 feet high, with a hem on each side and a one-inch-long triangular cross-section inden­tat~on (for flow redirection) that extends one-inch toward the inside and about one inch above the front lip. Full or partial side curtains can be hung from either side. The hood contains three 19.5 x 19.5-in. (495 x 495 mm) baffle filters positioned in the upper rear of the hood in front of a 17 x 11 in. ( 432 x 279 mm) rectangular duct opening. A wall extends from the top of the hood to t11e floor and beyond e~ch end. The insulated labo­ratory wall is 46 in. (1168 mm) behind the hood wall. A cross section of the 1 \abor~tory is shown in Figure 1.

The lowerJip of the hood is 78 in. (1981 mm) above the finished floor. The partial side curtains used extend from the lower lip of the hood to 33 in. (838 mm) above the finished

, floor (.gee I\igure 2). ,1.,.,, L '' 1;

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Figure l Cross 1sf!etionoftaboraf0rjahdiippliancelta1110pyhood coritiguraclolt ''·' · J : ••• ' · ·r: "5 ·' ' , ... 1 ,r .. ' · !• . f .:J :·10 :1 ·!.{',. J .11i 1 r;;'\1 .. :~ ~,

: ti )i ·IC' 11 ,;r;. :; ·'! :,,., , ~ ( I ,'.!•.~ The1 custon1i.~mgineered'•bat:Rshelfb&od· is••UL Li'sted at ,: ': '

31 . • •rt: . 4':$'2 cfrrtl ~2li3 Lis) for · Oboking' operatio:ns ·w'ith maximum

' ' :" i ;i appliance s'ur.fadettm)'leratu'Fj,:s of400°F'. (2040'0)! Thb-gritldle

·i .II . ·11 : ' station has art·o¥erall width ot1-4'ftH ih. (which-includes a 3 ,, • • • , :·1 I: , . i. . ., ft, 4 in. griddle bay) by 6 ft,.-7 i'n. hi~ll by J ft;;6 in. deep',' One

• n ' j I~ ' l '.J I 90" 1angle retu11n frames :the lloodi; perimeter ;opening: The

I ' •• . .i, material is 16.,;gauge':s'tainless"St~L A .1 6 x '4 'iti.: ·( 406 \}{ 102 ; , ,·1 , ' · ' : • ); 1 ,; • • ruin) :rectarigular ·dµdi '()pening is'. looated at the -b'ack ·of the

.~ •· " ' . hoocHmd centered·:over the ·cooking surface: TWO 20· xrf-0 in. 1;•: . , ,

1 11 17 l'I (l08-x254·mm)bafflefilters0are:installedatai1'attgleo'f60°

~ • • " , , 11 .. , 1 ·.t : ,1 -, , · . - " •. ~ .,, .. from·verticaUThe hood contains a flue bypass'Ht.1e front edge · , , ' · , ., , .

1 : c:·i. ,, 1. ofthe'hd>od 1is 57'in. (1448 mni) aborve th~ finished fl6dr. A

;, , .• , )J:~ cross section of· the laboratolly with the bitckshelf lfl.!idd;a:nd ..

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griddle setup is shown'iin Figure 3 .. '

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1"' J. i Capture and Containment Flc;>w Visu~li~a\i1911 'fl , I

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View of c;J.nbpy partial side tWtain. , . ·:: 1 ·. ' ~' ; . ! i. r I • ,.

UndenASX:M .J 704-96, airfloiW visualization/ may be enhanced using·1a smoke generator (theater-type fog;gltnera­tor), neutraU9 b4ay,antbubble generator1;dr other techniques, such as.schJlieren, to ehHance visibility1.0£the thermal P'lume rising from the 'heated cooking appl,iance. These· techrii'ques are particularly •usefuVat idle conditiorls and•witfi applialf¢es that produce little visib.le effluent. The ·exhaust flow• rate is

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Figure 3 Cross section of laboratory and applfrmcelbackshelf hood configuration.::

~l!\(- ~·1· BN-97-17-2

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From edge of hood

., .. Schliefon v_isualizatiQn_Jlf thermal plume · ,.

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From edge of appliance _

Figure 4 Thtesfwld _ c;apture 'and containment for 'siX­. element electric range ; 1op during· ·idle . cb{lditlons. 'I .

Spillage. of plume ..

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Figure ~- Spillage_ for ~{x clbmcnt clcctri~ rn.ngc dufing . idle conditions.

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reduced until spillage Bf the thermal plume and/<'.>r effluenfi~ observed. Any observed>lleak mOVin~ 1beyoi1d 'th~ee inches fronHhe hood face is•Construed to have eS\Saped from theil'lood, even if it may appear to; be drawn back into the1hood. The exhaust flow rate is then gradually increased in fine incre­

n~~nts until full .~a~tur~ ~t~d c?ntainmen,, are1acl~iev d. The airflow rate al l11s cond1t1011 1s referred to as. the thr~shold

I• 11 lJ ' ·, , ,...,J' exhaust airflow rate for complete capture and containment (see P1gures 4 anH S) ~· A.nol'her method ih the standard to deter­Mihe tfle idle c'aptti~e and containment flow rate is based .on a graphical anaJy~is·'df heat gain to space vs. exhaust flow rate.

. ' j " lrt the graphic'd ,method , the pb.i'nt ofcaP.tute_ and containmeil.t ' 'd · \ u.: · c , ~fl · h ' " I ) , I 1s sa1 to·occur at ·me pomt t ll ·rn ectton. - .. ·

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Test Process

: Jlwr.e, ai;e ,f~ur stgnjfi,c.ant m~asure}l\ep.ts that1 mus't be 111:i;ide un~eli the ASTl\1, 179,4-96: supply aiirflow. rate, SUJ!lplyi l}ir, :temper~tur~,, c;;~hip~st aix ,temp~~(!ture, and appl'iance input. e~er~. The .11irfl0Wi rate i~, r~qui)ie,d; .for,.!;~pture' and contain­iv-e.pt te~ts?.,and .~.l)j four mea_s,_urements are r~q,1.1ired for t~,b.eat g!J.in te!Jf~· .. ~·i '.Cl ; Jh; ·:,:r .,. rli ; :;; J"" •r,,

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Before the first test of the day is performed, the room · airflow is set to the required level and the appliance powered

on and allowed to come to cooking;;temperature. After the cooking temperature fa reached, the appliance cycles for a minimum time of one hour. The laboratory is then operated for

' a~other' hour, minimUfl;i, to ensure Stabilization' of the labora;. tory, hood, ductwork; and equipment.

c' For: subsequent tests at differe\ifaitflows,')he J~bod_toiy ; is st~blliz,ed for a miniJlium of ~ne-half~our prior to· recording -test data: Each idle.test is operated for a minin\urii of two hour:s for thermostatically · controlled appliances ~o ensure that energy input to the appliance has stabilize~_ for_the' selected

' :· exh(!USt ,flow rate. Cooking tests also require a minimum of20 ·- minutes, normally representing a minimum ofthree. cooking ': · ~ycl~s aiter ~ stabiliz~tion period. · · ,. · ~-,

; - Cooking tests are performed generally in accordance wlth the ASTM appliarn;:.e performance test ml:ltliods (e.g;;.ASTM fl 496-93, Standard Tesl Method for Pe~formance ofc;o~yec-

i \ ·~ • "- • . · I .

lion Ovens). The hoods and appliances were tested in an as-received condition; minor adjustfrtents were miade'to th'~m tb accommodate sensitivity testing. The appliance inputs are calibrated to operating conditions specified iri the ASTM stan­dard test method for each appliance type. For example, griddle controls wohld be set to operate at an average surface temper­ature-of,3500f (177°C). Charbroiler controls are set to operate at 6009F, - (316QC). Controls for non-thermostatically controlled appliances, such as a gas range tops, areset to 33%

' '6f ~!lmeplate i~put ta'ii'ng t_~ lllatch a 'typical operating energy

:'profile.

RESULTS ' .. : '1Table 1 shows the cook.ing and idle threshold capture and,

con1ilinmen.t'values for-a number of cooking ap.pliances under • I

a ·wall-niourited canopy liood and i ' ·ustom-engineered batk-sh'elf<"hood. When 'fhe 1 appliancethood combinaiio'n ' is taken intcf ac~oullt, rather'fhan the hO'od 'itself, cooking ca~ture and corrtainmeilt exhai1sf flow· rate vary significant_ly·; due to tl1e particuladppliance and'p'r6duct1 used: in'the opefation. .

'.L .. ' IJ•

Qiscussion of Results 'I' "J

Gas appliances usually required higher exhaust flow ;~t~s due to the additiofrof ~oitrbustiori prodhcts. The'volulrietric contribution to the effllueWfan'd thermal pl'1hn:e ranged from 12% to 104% Of the· dooking capture and c~htaidrfib'nt fid~ rate.':i ·. ~. i '.J.' ::iu •r ;·'··.J'.;'.., .

Tlie effluenfplur'n'e geiiera'.ted by a cooking pto6ess typ:i~1

cally required higher i5)(hfo1~t flow'rMtls' than the tidfo' condi'­ti,oll,.>However ,, ,in i the 'case., of lthe range tops., the· ·cooking pi:m:.e.s~~yielc}ed a lower· thr.'!shold capture an.ct dontainment • flqw rate d),le to transfer of the appliance energy to; the water in c_overed.!fauce pots instead.~fto the surrounding aiPli!v'here it w:ould,-normally contribute to a largere:ffluentplume:

! : : The addition of side panels< showed a reduttidn1ofoapttire and :containment flow rates. Inithe case of the elecftic chat"' hl:oiler, a ,Hi% reduction.w'asrshown at :idle cbnditi6n's:· Full t

BN-97-17-2 · .·11- ". 11

::

I !· I I I'

\..q '1" '·')< . 1J1 1;!TABLE1 ;» , Cooking,and .Idle Threshold Capture ·and Containment Values for Cooking' App!i~nces .

I • ..J : · • • "Jll " • I

~ i' ! ' : '; J • =~ i / ., '. . .' ! . · App. liance ""'~

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... •1 H..,vl .. Tvne ... ,~~ ·~"'"

.: .. Cooking Capture and Illle Capturt:;~nd

Containment Flow Rate, Containment Flow Rate, ~c~m/lj.n-ft (L/Sl>nt) stfmllin-ft (L/sl>m)

,1 !h Wall-Mounted Exhaust-Only Canopy "11 240 (372) 166 (257)

Gas Griddle (3-ft Length)' 1 " I) W ~nJMouiite(PExfiimst-Only Canopy 276 (427) .203(314) .. . .. IJ · Electric ~ryets. (B'!ttery ~f 3) .. , , , W~!\~Mqµqt~.d p15-Paust-Only Canopy 250 (387) 208 (322)

. .... - . Gas Fry~frt (Ba~t~,ry of 3) ~ ;: , Wall-Mounted Exhaust•Only Cat')opy V4 (486) 211 (3_27) ,;

Full-Size Elh!ctric Convection:oven WMl-MCiunted Exhaust-Only Canopy 125 (194). }IS..{17~)' ·

Full-Size G~s~ConvecU~n Ov~ri· ·' ~all-fy!ou~t~d.f:\~~~st-Only C~ll,9PY I 4~5 (395) l_ •\1,25Q (387) J·, ·\

WalhMounted1Exhaust-Only Canopy 210 025) \.,. ' \ 25'0·(387) . Gas Range, 33%·input f ·' WAH-Mounted ExhauS't~Only Canopy 340 (527) ·3·60'(557)

Wall"Mounted Exhaust-Only Canopy 410 (635) .. : ,...,.,28Q.;(4141 ,

Backshelf, .! 9,8,(151) -· 77..('11~)

Gas @riddle ((Ht Length) . Backshelf' 1'' 110 (170) 107 (165)

.. .. ' .. j ) ·, :1 i I TABLE 2 ' . . . 'j I • ·~ . : I

·' • .. : J·.

r.Threshold Capture and Containment for Range Tops Under Wall-Mounted, t. . , ·'Exhaust-Only Canopy Hood, with and without Quarter Side Panels ·

. . ' . I • " No Side Panel ' Partial Side Panel

" I ~cfm/lin-ft (L/sl>m) " s~fmtlin-ft (L/sl>m)

Appliance Cooking

Electric Range (33% input) 210 (325)

: : .. l Gas Range (33% input) 340 (527)

' J • • ; ' • I ~: ' I side panels created an µnstable flow regi!lle along the panel edges and c~sed spillage pf the cooking effluent. This condi­tion exisfFd for a wide range ol flow rate;s. Additional design work with the edge ofti)e panels. m~y alleviat~ or avqid sp.ill­age. Table 2 shows an ex,alJlIJl~pfho~ the thre,~hold. qf capture and containment changes in . the p

0

resence and absence of partial side panels on a wall-mounted, exhaust-only .canopy hood.

I 1; · ·..: )';, ;1

, i;pe ~ookjng prqcess1 is ev,4h1,ated i.m~er "static.'?: condi­

tiqns; A variabl,e p.ot taken,,il,ltq, a.cc.ouJ.lt by JJJ_, 710 or ASTM lJ,P~-96. i~t~y.effe,ct of a,q/~turbapqe. Distµrbances in the field can be created by supply diffuser location, supply air throw,

ki~?~rt:I: ~p~~er movemept, . ~11~ p~~ssyr~. irqpaJ.an,ce ,due to OJi'~ni~g, !!-f!P : ~losi,i;ig of q,~o.rs !ind p,aiSs~t1,r,0ugh wipdow_s. . .,.

" 1 l).isturbances are ¥ery ·'.difficult to ·simulate, let aldne mea&ure. an~ reproduce , Kitvhen employees ·and· the a:ctivHiesi th~y; are . involved in are1just ;as varied:. 'Prevfolis· atterhpts1 to sim\ljlate a .fypical ·kitchen eniployee?·s disturbance during a· cooking •pTOGess range fn:im a simple fan blowing across 'the front ·f!i~~1 of the, app.lianee, , to .. testing personnel walking at prescribed rates, to.hardwood :silhouettes moving back'a'nd fi;ir.th, on,a1rnil. This: adds additional turbulence to ah! operatitJn that is already very unstable. The UL and ASTM tests are

BN-97-17-2

~~ Cooking Idle ·

250 (387) 115 (17&). 120 (186)

360 (557) 225 (348) 245 (379/

conducted without a disturbance :for' rep~oducibility reasons, ~ut,the fact that the tests are undertake11 during full-load cook­ing .conditions adds a m!\rgi11 of sa;fety since th.is condition is not the norm in the field. An additional safety factor should be used to account for kitchen employee activity in-setting design values . n ' t.. :

Table ·) 1bomp~res the capture and containment vat~'es

l l I ~ · •c , •IJJI' • I calculareo for 11¥1 , the UL listed values-for each hood, and the , • , ~ • sJ ~ :1 '' t ,

ASTM tes 'values for the combinations .of appliances and ., , . • f;

hoods. In ~.os~: .~~se~1the lMC and UL rat~~ ate greater t~ . re<).u,ired. fhe differences between the IMC ,rates and the

A~~; ra~~~·\i...~.r~. ~r~~fest f~r t~e backshel~ ho9,d .. .The lM,C. rate for the electric griddle u~der. a backshelf hood was 207%, higher than the ASTM rate and it was 174% greater for the gas griddle. ' ' · '" · " ·

· ·Forthe canopy:hoCJd; the ,JMC:rate for' the :electric char­broiler was found fo be 95% higher th~ri the ASTM rate: The' IMP rates for electric fryers ·and foll-size electric convect'iori ownr were 60% higher'th~ri-'the tested ASTM tates. :i-Io'4ev~r; · thdMC rntes for the gas· ftlll-si':fo convecti~n uve1hind"ga$' range were lower than required under the ASTM test l>y 22%~ and 12%, respectively .

5

.. TABLE 3 r I, ,,.;

Comparison of Building Code, UL-Listed, ah~ ASTM ?apture.and Containment Values.under Full Cooking l .• oad

Appliance Type ,Hood Type .IM~ ·1 1 • u~ no·(at 6~0 qF) AS'fM F ;171)4!..9~·:

' scfmflin'-n ~ •t ·• scfm/lin-ft (L/sl'm) . scfr~(Llsl>m) '

l======================· =·~·===·=l ===================t===(Ll=s=~=~=)=·::::+======:::1:::::==~====::::====-=· =· ~·· Electric Griddle (3-ft Length) Wall~Mounted Exhaust-Only Canppy 300 (465) . 260. ~4{)3} ·-: , . 240 (~n):~ ~

Gas Griddle (3-ft Length) Wall-Mounted E~ha~st-Only Canopy '300 (465') · 260 (403) · ' 2'/6 (427) · .:"n >--~~~~~~~~~~~~~·~~~~~-'-~~~~~--jf--~~~~-1-~~~~~~-+---,-~~~~~~

Electric Fryers (Battery of 3) Wall-Mounted Exhaust-Only Canopy 1

' ',fod (619)1

260,(403) :• ' 250.(1.87) , . .--,..~~+-~~~~--,--i

Gas Fryers (Battery of 3) Wall-Mounted Exhaust-Only Canr,ipy ,~ 400 ((>.~ 9). 1 260 (40}), 314 (486), ·

Full Size Electric Convection Oven Wall-Mounted Exhaust-Only Canopy '. 200 (3'.10) 260(403) ) '125 (194)' .

Fuli size' Gas 'con~ection 0','e~ . ,• . w~1H\.1p4nt~d Exha~~t-Only Canopy'

Electric.Range (3,3% I,~pqt) , Wall~MQ.unted Exhau~t-Qnly Canopy : i 1:}00 (4,65)

Gas Range (33% Input) · Wall-Mounted Exhaust-Only Canopy. i 300{465) 260 (403) • ' 340 (527) .dJ'

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4'lP (635) ~~~~-;..- -~-~....,...-~~-'-----'~·'----&-~~-&--~rw~a1~1~~~~:1;U_u_11_~e_u_n_M~!~au_s~:L---+-~li+/Y~~-a1~~o_p_y--+~o-u_v_~..,..~~~. ~J ; ~o~l~VJJ : · - ·~

Ele<;t,rlic Gl'iddle (Ht I.iength) . Cu~tom-Engineered Back Shelf 300 ( 464) " · .1 134 (20?) ,. 1 , .. 98 (15,1) ~1 .,; ,, 1

Gas Griddle (3-ft Lenlrth) · i'• Custdrn-Ene:ineered B'ack Shelf 300 ( 464) 134 (207) 110 0 70) '--~~~~~-1.---. ~~---,-~~.......,. .. ~~~~~~~~--.-~~~~~~~~~~~~~~~~~~~~---·~

, • • I , "· Fot the backshelf hood the UL exhaust rates were 37%

~ .h • ..

higher for the electric gridClle and 22% ~igfier for tbe gas' grid-dle than tJ1e ASTM te~ t values: _or die· 6anopy 'hood,'th·e trL· rnce 'was insufiidtnrto exhaustt ie ooiH1\g·efflue1it fo1' the gas griddle, battery oftbre'e das fryers, gas r'a~ge 1dt 33% in p'ut: and electric charbroiler. ; 1

Idle C&C and Cooking C&C­lmplications for HVA€ Design ,I·

Kitchen exhaust systems have traditionally'been designed with cohstant-sp~(:d fan's'. Taole I dMa l;°llo'W ttiat there is often a signi fican t diffl!'rence'Jn ·exhaust'requi rements fpr idlev'ersus cooking conditi'O'ns. Durir g idle periods; !frost applia~ces require less exhaust to contain the thermal plume. The 'model 2ode organizatibns have interpreted th~ir codbs in the past to require the full exhaus

0

flow ra·te onfy whenco6king is being performed. Con$equ·ently, there may be opportunities to reduce 'the flow'rate dudng idle periods using a two-speed or' multi-speed :system. Spata (1993) reported idle periods as great as 80% of operating hours for certain ·appliances.

There may be significant energy and cost savings using a two-speed or multi-speed system, depending on whether the climate requires conditioning of the make-up air, the design strategy of the kitchen consultant, the hood/appliance combi­nations, and the amount of time the appliances are idle. Previ­ously, NFP A set the lower limit on the exhaust system at 1500 fpm (7.6 mis) without exception. Now they will allow less than 1500 fpm (7.6 mis) during idle periods (NFPA 1994).

Implications for Proposed ASHRAE Standard 154P

If a commercial cooking ventilation standard can be developed based on the particular cooking processes and appliance/hood combinations, instead of exhaust flow rates set by the style and dimensions of the exhaust hood, then the

6

industry can move toward 1 more realistic v3'.iues for kitchen ventilation while

1

1 ot coinpl-'om'ising1ope.iator health or s~fety . The prl:iposed ASH.Ri\E Stanaard 1'54-P 'VenHl~~fon for

. • i~ , . • I . I • '";

Commerc ial Cooking Operations, may .. el:ognize . ~h is

ap.i)roa~~ and. be b~sea in 'part 9;1 'the re~ult,~ ' from the ASTM

J 7,0~~96 test. metho? . Tl~~ASH~AE st~~~pard will likely ~ave re~uired values fo.r c9m,bi,ljlat~og1spf appl;iimc;es and hop4~~that w,ill

1be ~ealistic 11:u~ wH,l .aiso permit ,9ustom-engiry~1Jred

systems that are baseq on meftsur.ed data.The reported th,r_esh­

old values based on ASTM 1704-96, with appropriate safety

factOrs, may form. the,'basis:for reductions in make-up·andj exhaust airflow rates .that ·can conserve energy and, in many cases, reduce i;iapital cost. , , • 1

1-

CONCLUSIONS ' i

I '; '(: J I' ,,_

The data generated for threshold exhatisfairilo'W rates for

captu're and cbntainrr\ent using ASTM Fl 704-9'lJ gen~rally·. showed the IMC aria UL 'exhaust flow rate's-'are greafet•than

required. Furthermore, the threshold of capture and contain­

ment was lower for the electric appliances tested than for the

comparable gas appliances. For both gas and electric equip­

ment, significant differences were found in exhaust flow rates

between idle and cooking conditions. The addition of partial

side panels further reduced the exhaust flow rate during both

cooking and idle conditions. The reduced flow rates required under idle conditions present an opportunity to develop vari­

able-speed exhaust systems for commercial kitchen applica­

tions. The threshold values reported in this paper form a basis

for reductions in exhaust and make-up air requirements that can conserve energy and, in many cases, reduce capital cost

associated with commercial kitchen ventilation systems.

BN-97-17-2

ACKNOWLEDGMENTS performance of commercial kitchen ventilation systems.

L The authors;would like:tothal1Rc1Mr~·Wayne1~rill ofthe,1.l . ·,.~A~HRAE Transactions 101 (2), Electric Power Research ·Jnstitute ·and Ml'. Chari.es Claar of - Spata, A.J, and S.M. Turgeon. 1995. Impact of reduced lntei)mtiorral»Fa-eHity ·Management A!Tsociation' for the! finan- exhaust and ventilat~on rates at "no load" cooking con-cial and .teahn'ical support !"that •·inade the [~p-p,; ted re earch ditibrts in a commercial kitchen during winter operation. possible: Poofessor.Gary-Settles, 9irector.ofthe Gasllynam- _-- _.ASHRAE TransactiQDS 101(2). ic~ L3:~~frat(>t)/~ at P~nn Statel Vif.i~~rsify, was'_in~tr~ment3:liin . · , !JC. -i 99~;· UL Sta~dard :110, Standard for exhaust hnods for d1emonst~1tting that _the schlj~r~~ effect cpuJ~ 1 be used i,nir\l, coiniil~rcial cpbking equipment, 4t" ed. Northbrook, Ill.: l~rge-sc~l,e, ~.Y,~tem to-visu~l.ii~, capturr and, co~~~-iiu~ent, of Uncl~r~~iters Laboratories, Inc, ' -~ ' · -cooking ,e1

ffluellt. Dr. Leonclrd'.Weinste~, with v.1ewstar, Inc., .. . ~as the chief architect ali(hriiihufacturer Of•the schlieren ~IBLIO,GRAfHV. • 1

' ··-' • 1

system us!id at the CKV laboratory. In addition; Mr. Qon .pPRI, .:1996 .. ,Compleroial kitphen ,ventilatioJ~ · 1perform·ance Fisher wit~ yacific Gas and E leF,tric's li'ood S~~vice T;chnol- - report: .Gas fryers un"det canop~r hood. Electric -Power· ogy Center, Mr; Joseph Knapp with McDonald 's Corpora-ti·on,

1Resear~h Insttlute, TR-106493-vi)uly. . .·_ ' : Mr. Jiirl Kleva and Dr. Kevin Knappmiller ofl .l\omer_icb 0a·s 'J?!:Ril. 'I 99Q! C0131.1n·ercia l kitch_en 've·ntilatl~ 11_· p~erformail'c~ Association. Researdh, and. Mr. Fuoad Parvin ~~d ·Mr. Eliott,; ! report: ·.Elect ic fryers under cane_py hQod. , E lectric

Gordo? ~ith ffitlton Compa_ny,(~ormedy w~~h An_ieriCan Gas J • ,, -p~"'ie r Re.s~ar.c ln ~.titu~~ 1'.~- .l0649f-Vf•:,{u l~ . . ,: . ; Association Research) provided mvalu~ble techmcal support - EPRI. 1996. Commercia l kitchen ventilation perfo1:mance during 'the interlab testing phase of the 'research. · ~: 1 report: .Gas- griddle 1,mde_r candpy hd6d: .Eit\ct'ric ·P6wer'

11: 1 1 · - ) Re~earcq.Insti~ute, TR-106493-V31 July..,: · 1 _

REFERENCES EPRI. 1996. Commercial kitchen ventilation performance

AS,TM. 1996. ,:4\STM 1 ~t<}11d~r,d: ~ ~ 1701r-9,6, Standard test, .1 report: E.lecrric . gri~dl~ u~der, cap~PY hoog,._;r Electric ., w_eth9ff for.perfor_,rpancfJ 9f COIJ1{1;!y!Gia/ -!<itchen ven{jla,, . , 1 . Pqwer, ,~esearc:h Ip~tit~te, .TRi'!.9q~9,~-V 4 Ju l~., , . i-.•• x

t;on: 1sy,~tems. W~st Co~~ohocken, fA: A'?e.rican.Sofi-: Er~l,,J9~6. C01nm~r.c\~l1 ~ it~J.i.en yen~il ~!ion P~.rfp,~~an.?.<? . rl ety for .T~s.ting and M~tedals. ,

1 . , , . ·' • 11 • . • ;

11 •• • • •• re~9r~: .pas ,grid,dle _unde,r. p_ustog:i_ ~n&iA~ered bac;kshelf

NF,P.~. 1994_.1 ,NF~A ~~~nd!1.rd 96,XaP9{: ~emov.a~ Tro'!1 coq~- 1: hood., EleEtricJ~p}".e~ Re,~ear,?,?,, ~11stitute, J'R-106493-. ing equ ·pm~il l , . Section -2.2. " .. : Exception: "L'ow~r VS, July. · ,,, _ 1

exhaust air ~6 1 il~1es shali be p{ 1mitted during no foatl EPRI. 1996. Commercial kitchen ventilation. performance 'cooking conditl'l'.>ns , proviaed th·ey are suffici'ent to:c~p-' report: Electric griddle-under cu~t1>m ·engineered back-

· ·'. ti.ire ilnd remb'v~' flue gas~$ \ihd r~sidue Vl\pors '.frtii-n· shelf hood. Electric Power_ Re.search InsHtµte, TR-

" cooking'equipinent."Quiticf;'Mass~:NationalFire · Pro,.- .,,. , .19?4~J -~<?1 J~~Y· 1 i , , . ii'_, 1• .,.i: _- ' 1 ·1 rtection Association. : . 1 . ,, 'I:: EPRf.. . :19?6:: Cp1nme~cf.<J./,;k~tc~e,11, v~pt,ila!iBn perf~rmance

GQrdon, E.B., D.J. H6'rtoh:.· and F .A. ·Parv-in. 1994 .. Develop~ ,.XJ~PO!:ti F.{Ieqtr.~c; full ~j~e c;~~v~_ct~q,n ov.~-\1 u~?er canopy '.'''ment and application· of:a standard:test method fornthe) •. hoo4ff;E.kf~dc ~O"'.,!i~ ~ese~rrc\t Irs~it~~e, T~,-106493-

performance of exhaust hoods with.:c.ommercial ~ooking _ V7, July,. , . , , . , , , , . , appliances. ASHRAE Transactions 100 (2). EPRI. 1996. 99!Pmerpia! _kitc4~n ,v~,ntilatio,n performanc~,

Schmid, F.P., V.A. Smith, and R.T. S~ierc~y~~:.:J997. report:. qas convec~on pyen un-drr caqopy hood. Elec-. Schlieren flow visualization in commercial kitchen ven- tr,ic PoW{)_f:Research ~pstitute, T.R~,rn?49}: VS, .!u~Y;,JI till):~/oI\:.~~search, ASHRAE Trap§p.ctjor;is ,103 (2). 1 EPRI. 1996~,Minimum energy venfil~!ion for fastf,oo~ res-

S~ith1 y, ~· S~i~rczyna, and C. Cla.<J.r .. , ~~9?~ J\ppli_p.at_ion. taura1,1t kit;chens. Electric Power .~search Institute,. TR-,, :~nd, enha~cement of the s.tan,~ard t~M methqd f?r th~ 10667~,.,S,eptember. ·:- 1.1: _, "' : 1 _

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