ASHRAE HVAC APPLICATIONS SI CH 22-2015 PHOTOGRAPHIC MATERIAL FACILITIES.pdf

1、22.1CHAPTER 22PHOTOGRAPHIC MATERIAL FACILITIESStoring Unprocessed Photographic Materials 22.1Processing and Printing Photographic Materials 22.1Storing Processed Film and Paper . 22.3ROCESSING and storing sensitized photographic productsPrequires temperature, humidity, and air quality control. Manu-

2、facturers of photographic products and processing equipment pro-vide specific recommendations for facility design and equipmentinstallation that should always be consulted. This chapter containsgeneral information that can be used in conjunction with these rec-ommendations. See Chapter 31 for inform

3、ation on general industrialventilation.Special Warning: Certain industrial spaces may contain flam-mable, combustible, and/or toxic concentrations of vapors or dustsunder either normal or abnormal conditions. In spaces such as these,there are life-safety issues that this chapter may not completelyad

4、dress. Special precautions must be taken in accordance withrequirements of recognized authorities such as the National Fire Pro-tection Association (NFPA), the Occupational Safety and HealthAdministration (OSHA), and the American National StandardsInstitute (ANSI). In all situations, engineers, desi

5、gners, and install-ers who encounter conflicting codes and standards must defer to thecode or standard that best addresses and safeguards life safety.1. STORING UNPROCESSED PHOTOGRAPHIC MATERIALSVirtually all photosensitive materials deteriorate with age; therate of photosensitivity deterioration de

6、pends largely on the storageconditions. Photosensitivity deterioration increases both at hightemperature and at high relative humidity and usually decreases atlower temperature and humidity.High humidity can accelerate loss of sensitivity and contrast,increase shrinkage, produce mottle (spots or blo

7、tches of differentshades or colors), cause softening of the emulsion (which can lead toscratches), and promote fungal growth. Low relative humidity canincrease the susceptibility of the film or paper to static markings,abrasions, brittleness, and curl. Because different photographic products require

8、 different han-dling, product manufacturers should be consulted regarding propertemperature and humidity conditions for storage. Refrigerated stor-age may be necessary for some products in some climates.Products not packaged in sealed vaportight containers are vul-nerable to contaminants. These prod

9、ucts must be protected fromsolvent, cleanser, and formaldehyde vapors (emitted by particle-board and some insulation, plastics, and glues); industrial gases;and engine exhaust. In hospitals, industrial plants, and laboratories,all photosensitive products, regardless of their packaging, must beprotec

10、ted from x-rays, radium, and radioactive sources. For exam-ple, films stored 8 m away from 100 mg of radium require the pro-tection of 90 mm of lead.2. PROCESSING AND PRINTING PHOTOGRAPHIC MATERIALSVentilation with clean, fresh air maintains a comfortable workingenvironment and prevents vapor-relate

11、d complaints and health prob-lems. It is also necessary for high-quality processing, safe handling,and safe storage of photographic materials.Processing produces odors, vapors, high humidity, and heat(from lamps, electric motors, dryers, mounting presses, and high-temperature processing solutions).

12、Thus, it is important to supplyplentiful clean, fresh air at the optimum temperature and relativehumidity to all processing rooms. ASHRAE Standard 62.1 speci-fies 5.0 L/(sm2) of exhaust for darkrooms in Table 6-4.Air Conditioning for Preparatory OperationsDuring receiving operations, exposed film is

13、 removed from itsprotective packaging for presplicing and processing. Presplicingcombines many individual rolls of film into a long roll to be pro-cessed. At high relative humidity, photographic emulsions becomesoft and can be scratched. At excessively low relative humidity, thefilm base is prone to

14、 static, sparking, and curl deformation. The pre-splice work area should be maintained at 50 to 55% rh and 21 to24C db. Room pressures should cascade downward from areas ofhigher air quality to areas of lower air quality (clean to dirty).Air Conditioning for Processing OperationsProcessing exposed f

15、ilms or paper involves using a series of tem-pered chemical and wash tanks that emit heat, humidity, and vaporsor gases (e.g., water vapor, acetic acid, benzyl alcohol, ammonia,sulfur dioxide). Room exhaust must be provided, along with localexhaust at noxious tanks. To conserve energy, air from pres

16、surizedpresplice rooms can be used as makeup for processing room exhaust.Further supply air should maintain the processing space at a maxi-mum of 24C dry bulb and 50 to 55% rh.The processed film or paper proceeds from the final wash to thedryer, which controls the moisture remaining in the product.

17、Too lit-tle drying causes film to stick when wound, whereas too much dry-ing causes undesirable curl. Drying can be regulated by controllingdrying time, humidity, and temperature.The volume of supply air should be sufficient to achieve the designcondition. Airflow should be diffused or distributed t

18、o avoid objec-tionable drafts. Apart from causing personnel discomfort, drafts cancause dust problems and disturb the surface temperature uniformityof drying drums and other heated equipment. Supply and return airopenings should be properly positioned (1) for good mixing and dilu-tion of the room ai

19、r, (2) to ensure efficient removal of fugitive vapors,and (3) to avoid short-circuiting of supply air into return or exhaust airopenings. For automated processing equipment, tempered outdoorair should be supplied from the ceiling above the feed or head end ofthe machine at a minimum rate of 70 L/s p

20、er machine (Figure 1). Ifthe machine extends through a wall into another room, both roomsneed to be exhausted.An exhaust system should be installed to remove humid or heatedair and chemical vapors directly to the outdoors (process streams typ-ically must comply with regulations pursuant to the Clean

21、 Air Act).The room air from an open machine or tank area should be exhaustedto the outdoors at a rate sufficient to achieve at least the vapor dilutionlevels recommended by the American Conference of GovernmentalIndustrial Hygienists (ACGIH 2010). An exhaust rate higher than thesupply rate produces

22、a negative pressure and makes the escape ofThe preparation of this chapter is assigned to TC 9.2, Industrial AirConditioning.22.2 2015 ASHRAE HandbookHVAC Applications (SI)vapors or gases to adjoining rooms less likely. Depending on the pro-cess chemistry, local exhaust hoods may be needed at uncove

23、red sta-bilizer tanks or at the bleach fix tanks (Figure 1). The exhaust opening should be positioned so that the flow ofexhausted air is away from the operator, as illustrated in Figure 2.This air should not be recirculated. The exhaust opening shouldalways be as close as possible to the source of

24、the contaminant forefficient removal see ACGIH (2010) for more information. For aprocessing tank, the exhaust hood should have a narrow opening atthe back of, level with, and as wide as the top edge of the tank.Processing tanks are often covered to reduce evaporation ofheated processing chemical sol

25、utions (approximately 38C).Covers on photographic processing equipment and chemical stor-age tanks can effectively minimize the amount of gases, vapors, ormists that enter the work area. If the processing tanks are enclosedand equipped with an exhaust connection, the minimum room airsupply and exhau

26、st rates may be reduced compared to an opentank (Figure 3).A sulfide-toning sink should have a local exhaust hood to venthydrogen sulfide. However, sulfide toners are rarely used nowexcept for some specialized art processing and archival microfilmprocessing. The exhaust duct must be placed on the si

27、de oppositethe operator so that vapor is not drawn toward the operators face.Air distribution to the drying area must provide an acceptableenvironment for operators as discussed in Chapter 9 of the 2013ASHRAE HandbookFundamentals and ACGIH (2010). Exposedsides of the dryer should be insulated as muc

28、h as is practical toreduce the large radiant and convected heat gain to the space.Exhaust grilles above the dryer can directly remove much of itsrejected heat and moisture. Supply air should be directed to offset theremaining radiant heat gain to the space.Using processor dryer heat to preheat cold

29、incoming air duringwinter conditions can save energy. An economic evaluation is nec-essary to determine whether the energy savings justify the addi-tional cost of the heat recovery equipment.A canopy exhaust hood over the drying drum of continuouspaper processors extracts heat and moisture. It is im

30、portant to followthe processing equipment manufacturers recommendations forventing the dryer section of the processor. Whenever possible, dryervents should be exhausted to the outdoors to prevent build-up ofexcessive temperature and humidity in the workplace.When drying motion picture film, exhaust

31、should draw off vaporfrom the solvent and wax mixture that is normally applied for lubri-cation.Air Conditioning for the Printing/Finishing OperationIn printing, where a second sensitized product is exposedthrough the processed original, the amount of environmental controlneeded depends on the size

32、and type of operation. For small-scaleprinting, close control of the environment is not necessary, except tominimize dust. In photofinishing plants, printers for colored prod-ucts emit substantial heat. The effect on the room can be reduced byremoving the lamphouse heat directly. Computer-controlled

33、 elec-tronic printers transport the original film and raw film or paper athigh speed. Proper temperature and humidity are especially impor-tant because, in some cases, two or three images from many separatefilms may be superimposed in register onto one film. For bestresults, the printing room should

34、 be maintained at between 21 and24C and at 50 to 60% rh to prevent curl, deformation, and static.Curl and film deformation affect the register and sharpness of theimages produced. Static charge should be eliminated because itleaves static marks and may also attract dust to the final product.Mounting

35、 of reversal film into slides is a critical finishing oper-ation requiring a 21 to 24C db temperature with 50 to 55% rh.Fig. 1 Open Machine VentilationFig. 2 Open-Tray Exhaust Ventilation from Processing Sink Fig. 3 Enclosed Machine VentilationPhotographic Material Facilities 22.3Digital printing op

36、erations use equipment that generates signifi-cant heat. An exhaust system can be directly connected to the laserprinter to remove heat at a flow rate specified by the equipmentmanufacturer. Sufficient room ventilation is required so that appli-cable occupational exposure limits are not exceeded and

37、 a favorableoperating environment is maintained.Particulates in AirAir conditioning for most photographic operations requires 85%efficiency disposable bag-type filters with 30% efficiency prefiltersto extend the bag filter life. In critical applications (such as high-altitude aerial films) and for m

38、icrominiature images, filtering of for-eign matter is extremely important. These products are handled in alaminar airflow room or workbench with 95% efficiency HEPA fil-ters plus 30% efficiency disposable prefilters.Other Exhaust RequirementsA well-ventilated room should be provided for mixing the c

39、hem-icals used in color processing and high-volume black-and-whitework. The room should be furnished with movable exhaust hoodsthat provide a capture velocity as defined in ACGIHs (2010) Indus-trial Ventilation for the worst-case scenario. Modern photographicminilabs often use canisters of premixed

40、processing solutions, so nochemical mixing is necessary.If prints are lacquered regularly, a spray booth is needed. Con-centrated lacquer spray is both hazardous and very objectionable topersonnel; spray booth exhaust must be discharged outdoors.Processing Temperature ControlLow processing volumes a

41、re typically handled in minilabs,which are often installed in retail locations. Minilabs are usuallyself-contained and equipped with temperature controls, heaters, andpumps. Typically, the owner only has to connect the minilab towater, electricity, exhaust (thimble connection), and a drain.Higher-vo

42、lume processing is handled with processors that comefrom the manufacturer complete with controls, heat exchangers,pumps, and control valves designed for the process that the ownerhas specified. Electricity, hot water, cold water, drainage, and steammay be required, depending on the manufacturer, who

43、 typically pro-vides the specifications for these utilities.3. STORING PROCESSED FILM AND PAPERStorage of developed film and paper differs from storage of rawstock, because the developed materials are no longer photo-sensitive, are seldom sealed against moisture, and are generallystored for much lon

44、ger periods. Required storage conditions de-pend on (1) the value of the records, (2) length of storage time, (3)whether the films are on nitrate or safety base, (4) whether the pa-per base is resin coated, and (5) type of photographic image.Photographic materials must be protected against fire, wat

45、er,mold, chemical or physical damage, high relative humidity, andhigh temperature. Relative humidity is much more critical than tem-perature. High relative humidity can cause films to stick together,(particularly roll films, but also sheet films). High humidity alsodamages gelatin, encourages the gr

46、owth of mold, increases dimen-sional changes, accelerates the decomposition of nitrate support,and accelerates the deterioration of both black-and-white and colorimages. Low relative humidity causes a temporary increase in curland decrease in flexibility, but when the humidity rises again, thesecond

47、itions are usually reversed. An exception occurs when motionpicture film is stored for a long time in loosely wound rolls at verylow humidities. The curl causes the film roll to resemble a polygonrather than a circle when viewed from the side. This spokinessoccurs because a highly curled roll of fil

48、m resists being bent in thelength direction when it is already bent in the width direction. Whena spoky roll is stored for a long time, the film flows permanently intothe spoky condition, resulting in film distortion. Very low relativehumidity in storage may also cause the film or paper to crack orb

49、reak if handled carelessly.Low temperature (23 to 10C) is desirable for film and paperstorage if (1) the relative humidity of the cold air is controlled, and(2) the material can be sufficiently warmed (for 2 to 8 h) beforeopening to prevent moisture condensation. High temperature canaccelerate film shrinkage, which may produce physical distortionsand the fading of dye images. High temperature is also detrimentalto the stability of nitrate film.Film LongevityThe American National Standards Institute (ANSI StandardIT9.11) defines longevities of films with a life expectancy (LE)ra