EXHAUST DUCT
All ventilation duct to be fabricated of Type 1, Grade 1 or Type 2, Grade 1, high impact P.V.C. Extruded Type 1 P.V.C. duct 6" diameter to 18" diameter will be acceptable where applicable.

All KCH systems are designed in accordance with the recommended practice of the American Conference of Governmental Industrial Hyglenigts and fabricated in accordance with (SMACNA) Sheet Metal and Air Conditioning Contractors National Association, manual on Thermo Plastic Construction.

All P.V.C. used in fabrication of KCH products is unplastisized and conforms U.S. Commercial Standard CS 201-55 and also ASTMD 1784-69, Type II, Grade 1 LP-535b, Type II, Grade GU. All P.V.C. conforms to ASTM standard D 635 and has a flame spread rating of 20.

FITTINGS--ROUND & RECTANGULAR DUCT
Flanges - To be made of P.V.C. Type 1 or Type 2 angle material formed and continuously welded to duct. 1.5 X 1.5 x .1875" (3/16) angle and 2" x 2" x .250" angle are used in relationship to duct sizes. Bolt holes to be .3125" (5/16) diameter for .25" stainless steel bolts and no more than six (6) inches apart on centers. Gasket material to be of soft mastic type or form P.V.C.

Sleeves - To be formed from three (3) inch wide flat P.V.C. material of a thickness equal to or greater than the wall thickness of duct to be joined. Weld to one end of duct section leaving one half the sleeve length for adjoining section to slip into.

Elbows - To have a minimum center line radius of 1 1/2 times diameter unless field conditions make it impossible. Ninety degree elbows to have five (5) gores and forty-five degree elbows to have three (3) gores.

Branches - To enter main at no more than forty-five degrees (thirty degrees preferred) to direction of flow and wherever practical to enter on an enlarging taper section. Branches should not enter opposite each other. Branches to be continuously welded to main.

Taper Section - 1" change in diameter to 5" in length, where practical.

CONSTRUCTION - RECTANGULAR DUCT
All straight lengths to have formed corner construction for maximum strength. This includes taper sections where practical. Elbows to have welded corner construction.

INSTALLATION
All joints to be flanged or sleeved and made air-tight. Sleeves may be welded or cemented. Flanges joints should be provided at all connections where dismantling may be required. Ductwork should be fitted with saddle bands at 8' to 12' centers suspended with all thread rod. Ductwork should also be suspended at each change in direction.

WELDING
Welding shall be done by the hot air fusion welding method for P.V.C. and hot gas fusion welding method for poly propylene. Ductwork, hoods and similar air passage enclosures must be finished completely air and water tight. Ductwork shall be completely free from cracks distortion or other imperfections.

EXHAUST BLOWERS
Exhaust blowers shall be centrifugal, arrangement 9 with backwardly inclined wheels Type NH and Type CI Paddle Wheel as manufactured by KCH Services, Inc. Wheels shall be steel with FRP coating, fiberglass or stainless steel. Coating will be spark tested to insure integrity. Housing shall be constructed of Type 2, Grade 1, high impact P.V.C. Frames shall be steel with coating. All Blowers shall be equipped with a vacuum formed inlet cone, drain, access door, O.S.H.A. approved belt and shaft guards and flexible inlet and flanged outlet. All exhaust blowers shall carry a one year replacement guarantee against failure due to corrosion. Fans are to be balanced prior to shipment.

FUME SCRUBBERS
KCH Services' wet type fume scrubbers shall meet the following specifications:

MATERIAL
Fume scrubbers shall be constructed of Type 1, or Type 2, P.V.C. Polypropylene, or FRP. Scrubbers to be complete with epoxy coated steel base of sufficient strength to make unit self supporting. All in-scrubber piping shall be P.V.C. or Polypropylene. Spray nozzles shall be full cone, non-clogging, open orifice type.

SCRUBBING & ELIMINATING SURFACE
A packed scrubber bed at least 12" deep shall be provided. The packing material shall consist of corrosion resistant, non-clogging packing media shapes with a minimum surface area of 40 sq. ft. per cu. ft. The scrubbing section shall be constantly wetted by non-clogging, continuous flow spray nozzles, and overhead weir. A minimum 8" deep mist eliminator section shall be provided. This shall consist of vertically mounted P.V.C. eliminators providing at least four (4) changes in direction of the air flow and eliminate entrained water from the air stream before it leaves the scrubber. Scrubbers shall be sized for a maximum of 500 F.P.M. at the packing face.

A pre-wet section shall be provided at the entrance to the scrubber consisting of a bank of spray nozzles headed into the air stream. The nozzles shall be sufficient in number to blanket the inlet cross section with mist. Overhead weir to be used when complete, continual saturation is required.

A flow meter shall be provided at the fresh water inlet. Water, tight access doors shall be provided to permit easy access to scrubber bed and eliminators for maintenance purposes and to permit inspection while in use. Inlet and outlet openings shall be flanged.

EXHAUST HOODS
All exhaust hoods are to be fabricated of Type 1 or Type 2, Grade 1, high impact P.V.C., poly propylene or FRP. The basic hood shape shall be fabricated of .1875" (3/16) thick P.V.C. All P.V.C. sheet used as reinforcing to be .25" (1/4) thick P.V.C. angle, spaced not greater than 12" c.c. shall be used internally to reinforce slot dividers on vertical type hoods.

All lip type hoods to have top and bottom of slot section reinforced with .25" (1/4) P.V.C. Additional P.V.C. reinforcing shall be used as required to strengthen the hood at critical points and prevent warping. P.V.C. exhaust hoods shall be fabricated basically by hot welding, but welds will not be allowed at corners along the length of the hood. All such corners are to be heat formed.

All welded joints shall be welded inside and out whenever possible. all hoods are to be equipped with a means of preventing liquid from accumulating in the bottom. Hoods having a plenum lower than the lowest slot shall have a drain crease in the bottom with a 1" threaded coupling. All hoods shall be equipped with an outlet connection as indicated on the drawings.