explosion proof air conditioning
explosion proof air conditioning
BIRDWELL MODEL BFPD1300, BFPD3300, BFPD4500
MICRO-FILTERTMIII
DUAL FAN FILTER/PRESSURIZATION UNIT
INSTALLATION, OPERATION, AND MAINTENANCE INSTRUCTIONS
PURPOSE:
The Birdwell Micro-FilterTMIII filter/pressurization units were designed to meet the NFPA 496 code for purged control rooms in Class I (II) locations and are listed by ETL Testing Laboratories, Inc. These units provide a clean, pressurized environment for computerized control rooms located in refineries, chemical plants, pulp and paper mills, or other areas where corrosion and dust particles pose a hazard to delicate instrumentation.
The Micro-FilterTMIII unit may be utilized with Birdwell heating/cooling units for total environmental control of temperature, humidity and air purity.
CONSTRUCTION:
Unit cabinets are manufactured using 16 gauge (.060) galvanized paint grip steel. Doors are double wall, internally insulated for quiet operation. The assembly is prime coated, then given two coats of polyurethane enamel for corrosive atmosphere protection.
The pressure control balancing damper is made of .060 stainless steel and the backdraft dampers are made of .060 aluminum. The hinges are the stainless steel continuous type.
The return air grille is located at the bottom of the unit and is made of stainless steel. The supply air grille is located on top of the unit and is made of stainless steel.
A standard eighteen inch diameter bolt ring flange is located on the top rear for mounting a matching ring flanged fresh air stack. The stack is an optional item available in stainless or galvanized steel.
The units are supplied with two, direct drive, non-sparking, fans. The purge air fan is rated for 1300, 3300, or 4500 CFM. The pressurization blower is rated for 600 CFM @ 4.3" W.G.S.P. @ 60 hertz.
A spring loaded frame is used to hold the high performance "final" filter and provide a clamping action to give a positive seal between the final filter gasket and the upper portion frame perimeter. This system prevents leakage of particulate matter around the filter.
Two stainless steel filter cartridges containing approximately 66 pounds each of impregnated activated alumina media is located above the primary filter rack. The two containers have a total surface area of 3.98 square feet with a total volume of 2.64 cubic feet.
The top and bottom of the chemical filter cartridges are made of stainless steel perforated sheet metal with 3/32" holes on 9/64" staggered centers to contain the media and permit air passage at 150 F.P.M. velocity @ 60 hertz.
A crank actuated patented "Micro-SealTM" system (patent #5,447,544) prevents the air from bypassing the chemical filters thus assuring 100% filtration.
The stainless steel chemical filter cartridges may be serviced from the unit front or rear. If serviced from the rear, a fork lift may be used to off-load and on-load the filter cartridges from outside the building.
Recessed handles and removable end cover are provided on the chemical filter cartridges for ease of handling and for changing chemical filter media.
The standard system is provided with four stages of filtering consisting of three types of filters. The first, or "primary filter" being downstream from the room air/pressurization air mixing plenum. The purpose of this filter is to remove and retain the larger particulate matter entering the system.
The second, or "chemical" filter is immediately downstream from the primary filter. The purpose of this filter is to remove and retain corrosive gases from the air such as hydrogen sulfide (H2S), sulphur dioxide (SO2), etc.
The third, or "re-filter" is downstream from the chemical filter. The purpose of this filter is to remove and retain particulate matter that may become dislodged from the chemical media before it reaches the high performance filter.
The fourth, or "final" filter is the high performance filter. The purpose of this filter is to remove and retain microscopic particulate matter.
PRIMARY FILTER AND REFILTER:
FILTER TYPE 2 inch 30% efficient, pleated, disposable type consisting of a non-
woven cotton and synthetic fabric media, media support grid and enclosing frame. The filter is listed by Underwriter's Laboratories as Class 2.
MEDIA Filter media is of the non-woven cotton fabric type. The filter
DESCRIPTION media has an average efficiency of 30-35% on ASHRAE Test Standard 52-76. It has an average arrestance of 92% in accordance with that test standard.
The effective filter media is 3.1 square feet of media per 1.0 square foot of filter face area and contains 10 pleats per linear foot. Initial resistance at 165 fpm approach velocity is .03" w.g. @ 60 hertz.
FILTER The media support is a 28 gauge expanded metal support grid
CONSTRUCTION with an effective open area of 95%.
DESCRIPTION
The support grid is bonded to the filter media to eliminate the possibility of media oscillation and media pull away.
The media support grid is formed in such a manner that it effects a radial pleat design, allowing total use of filter media.
The enclosing frame is constructed of a rigid, heavy-duty, high wet-strength beverage board, with diagonal support members bonded to the air entering and air exiting side of each pleat, to ensure pleat stability. The inside periphery of the enclosing frame is bonded to the filter pack, thus, eliminating the possibility of air bypass.
FILTER U.L. Class 2 rated on ASHRAE Test Standard 52-76 at 30-35%
PERFORMANCE efficiency, arrestance is 92% and may be operated at varying ve-
DATA locities up to 500 fpm.
CHEMICAL FILTER:
FILTER TYPE Impregnated activated alumina media.
MEDIA Impregnated activated alumina is a chemisorbant media designed
DESCRIPTION to remove gaseous vapors such as H2S, SO2, SO3, ethylene (olefins), formaldehyde and methyl/ethyl mercaptans.
It also has the ability to adsorb and absorb products of aldehydes, light organic vapors, organic acids and inorganic acids. Impregnated activated alumina removes gaseous contaminants from the air stream by adsorption, absorption and chemical oxidation.
PHYSICAL A. Purple built-in color indicator.
PROPERTIES
B. Spherical pellet shape.
C. 1/8" - 3/16" mean particle diameter.
D. Pressure drop at 50 f.p.m. linear velocity - 1.6". w.c./ft.
E. 50 lbs. bulk density pre cubic foot.
F. Active ingredients - potassium permanganate (KMnO4), 4% by weight.
G. Inert ingredients - alumina (AL2O3).
H. Underwriter's Laboratories, Inc. Class I rating.
I. Absorbed/adsorbed pollutants will not out gas.
J. 60 - 180 minutes each time.
K. Crush strength - 5 lbs. minimum.
IMPREGNATED ACTIVATED ALUMINA
ISA STANDARD FOR GAS CONTAMINATIONS - 6/20/89
ISA s71.04
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GI |
G2 |
G3 |
GX |
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SEVERITY LEVEL |
MILD |
MODERATE |
HARSH |
SEVERE |
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<300 |
<1000 |
<2000 |
>2000 |
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GAS CONCENTRATION (PARTS PER BILLION)
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H2S |
HYDROGEN |
<3 |
<10 |
<50 |
>50 |
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SULFIDE |
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SO2 |
SULPHUR |
<10 |
<100 |
<300 |
>300 |
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DIOXIDE |
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Cl2 |
CHLORINE |
<1 |
<2 |
<10 |
>10 |
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NOX |
OXIDES OF |
<50 |
<125 |
<1250 |
>1250 |
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NITROGEN |
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NH3 |
AMMONIA |
<500 |
<10,000 |
<25,000 |
>25,000 |
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O3 |
OZONE |
<2 |
<25 |
<100 |
>100 |
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HF |
HYDROGEN |
<1 |
<2 |
<10 |
>10 |
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FLUORIDE |
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CLASSIFI- MILD An environment sufficiently well controlled such
CATIONS (G1) that corrosion is not a factor in determining equipment reliability.
MODERATE An environment in which the effects of corrosion are
(G2) measurable and may be a factor in determining equipment reliability.
HARSH An environment in which there is a high probability
(G3) that corrosive attack will occur. These harsh levels should prompt further evaluation resulting in environmental controls or specially designed and packaged equipment.
SEVERE An environment in which only specially designed
(GX) and packaged equipment would be expected to
survive. Specifications for equipment in this class are a matter of negotiation between user and supplier.
METHOD OF The above corrosion rates were determined from coupon tests in
MEASUREMENT which copper coupons were exposed to the contaminant gases for 30 days.
FINAL HIGH PERFORMANCE FILTER:
FILTER TYPE High performance deep pleated, disposable.
MEDIA Micro-fine glass fiber.
DESCRIPTION
FILTER The media is arranged in deep-pleat design. The filter holding
CONSTRUCTION frame is made from 16 gauge galvanized steel. The media pack is
DESCRIPTION sealed into the frame with gaskets and four spring type positive
sealing fasteners.
FILTER 1. Efficiency rating based on ASHRAE 52-76 is 65% effective fil-
PERFORMANCE tration. Range includes particle size down to 0.3 microns.
DATA
2. Initial pressure drop is .13 inches water gauge at 275 feet per minute air flow.
CONTROLS:
The building pressure gauge is the Magnehelic type. Pressure range is 0.0 to 0.25 inches w.c. with an accuracy of plus/minus two percent of full scale.
Time delay relays are the solid state type adjustable from zero to eight minutes. The control relay is a double pole, double throw 24 volt plug in type. Motor contactors may be two or three pole, depending upon whether the motors are single or three phase.
The optional gas detection and optional remote alarm relays are single pole double throw 24 volt plug in types.
INSTALLATION:
Provide an opening through an outside wall level with the inside floor approximately 42 3/4" wide and 50 1/2" high to provide 1/4" clearance all around (opening must be squared). Optional 11 gauge mounting sleeve with threaded bolt holes is available. See dimensional drawings.
When locating the unit, make sure there are no obstructions where the fresh air stack will be located and that the stack will clear the roof overhang (if any).
Remove the shipping cover from the top rear of the unit. Bolt the fresh air stack over this opening.
Attach 1/8" stainless steel aircraft type cables to the attach points near the fresh air stack cap. Apply silicone rubber caulking to the stack mounting flange ring. Lift stack in position and bolt the matching flange rings together. Be sure the stack is plumb, then secure the guy wires.
After installation, carefully apply silicone rubber caulking between the unit and the wall opening to prevent water or air leakage.
Electrical options are: 208/230/1/60, 208/230/3/60 or 460/3/60. 50 Hertz models are also available. Make electrical connections according to the wiring schematic provided.
OPERATION:
Remove pressurization blower door and purge fan filter grille. With power applied to the optional gas detection relay, turn the system switch to the purge position for indefinite purge time. In this position, only the purge fan is energized allowing relatively safe purging of possibly hazardous gases from the building.
Check rotation of the purge fan and pressurization blower. Reverse rotation on three phase motors by reversing any two power leads. Close the filter grille on purge fan and replace pressurization blower door.
With the system switch in the "on" position, the pressurization fan in energized. If the building pressure is at .15" w.c., the green normal pressure light is energized and the purge fan is off. If the building pressure drops below .1" w.c., the green normal pressure light is de-energized for 5 seconds. Then the purge fan is energized. If the building pressure is not restored in 45 seconds, the (optional) remote alarm bell and remote alarm relay will energize until the pressure is restored to .15" w.c. When the pressure is restored, the purge fan and amber low pressure light de-energize and the green normal pressure light is energized.
The system has two separate power supplies. If something happens to the primary pressurization power supply, the unit will automatically energize the purge fan.
MAINTENANCE:
The Birdwell Micro-FilterTMIII filter/pressurization units are easy to maintain since the blowers are direct drive with no belts to break or wear out.
However, the filters must be kept in a clean condition in order that they not impede air flow to the extent that the required air volume is insufficient to maintain building air pressure.
We recommend that the filters be checked on a monthly basis until the rate of filter loading has been determined. The chemical filter life is determined by a laboratory analysis. To replace the filters or filter media, remove the filter access door located on the unit front. If desired, the chemical filter may be removed from outside the building by utilizing the chemical filter access door located on the rear side of the unit.
To remove the primary filter, gently slide the media out of the guide rails to prevent excessive amounts of dust from falling into the machine or on the floor. Make sure the dense side of the new filter is in the down position (upstream) and carefully slide it into the guide rails without leaving any gaps between the filter and guides that air could bypass the filter through.
The chemical filter is tightly secured in place by a "Micro-SealTM" system. To remove the chemical filter, loosen the chemical filter cartridge by turning the "Micro-SealTM" crank in the direction indicated. Carefully remove the chemical filter cartridge using the filter cartridge recessed handles provided. Use a forklift or dolly to transport the chemical filter cartridge. Remove cartridge cover plate and replace spent media with the new material very gently to create as little dust from the material as possible.
Before re-installing the chemical filter, inspect the filter gasket on the leaving side of the chemical filter cartridge to assure proper "Micro-SealTM". Also check chemical filter "Micro-SealTM" framework to make certain that surface of framework is clean and smooth to assure good seal between framework and filter gasket.
Install the replenished chemical filter and turn "Micro-SealTM" crank in direction indicated to accomplish tight seal between the chemical filter and "Micro-SealTM" framework.
To remove the final high performance filter, remove the four spring type fasteners. Slide the filter out. Install the new filter media pack and re-install four spring fasteners. Reinstall large service door.
If the motors have grease fittings, lubricate according to the instructions on the motor. If no fittings are visible, the motor has sealed bearings.
CAUTION: The motors may have automatic overload protection, and could start without warning, so be sure the main power has been disconnected before working on any part of the unit.
FILTER MAINTENANCE GUIDELINES:
The following information provides Birdwell guidelines as to determining when to change filters and/or filter media in the Birdwell Micro-FilterTMIII pressurization unit.
Due to the variety of chemicals and concentrations that may be encountered, plus the variety of environmental conditions possible, there is not a clear-cut method for determining when to change either the chemical or particulate filters in the Micro-Filter unit. However, initially, until the rate of filter loading has been determined, Birdwell recommends that the particulate filters be checked on a monthly basis. The key factor in determining particulate filter loading is the magnehelic differential pressure gage, which indicates the pressure drop across all filters. With new filters, the static pressure drop is approximately 3.6" W.C.; therefore, when the gauge reads 3.9" W.C., it is recommended that both the primary filter and re-filter be inspected, and changed if needed. If after changing both 2-inch 30% pleated filters, and you discover that the pressure drop is still above 3.9", the high performance filter should also be inspected, and changed if needed.
The pressure drop across the chemical filter should not vary appreciably, therefore the differential pressure gauge is only useful in determining filter loading of the three particulate filters (the two 30% type, and the single high performance type). The chemical media shipped with your unit was Mk 2 pellets, which is made of inert alumina (AL2O3) pellets, and activated and impregnated with potassium permanganate (KMnO4). This particular media has a built-in color indicator; therefore visibly checking the chemical media is probably the most practical method for determining when it should be replaced. The outside portion of the media pellets will automatically appear to be brown as soon as they are exposed to air. However, the internal color can be checked by placing a small sample (1 teaspoon) of the Mk 2 pellets into a clear glass of water. If the water turns purple, the media is still good; if it turns brown or remains clear, the active ingredient (KMnO4) is spent, and a change is recommended. However, to determine the approximate media life cycle, a sample of the Mk 2 can be chemically analyzed to determine the percent of active ingredients remaining.
If assistance is needed to determine the expected media life cycle, send Birdwell a sample (approximately one tablespoon) in a sealed ziplock bag and test results indicating the remaining percentage will be reported by fax. It is recommended that the media be changed when the KMnO4 remaining is <1.4%.
The media sample should be obtained from the center of the cartridge. The recommended procedure is as follows:
If any problem is encountered that is not covered in these instructions, or for any question that might arise, call The Birdwell Company in Houston Texas (281) 492-1786.