TT-933: Compressed Air Requirements

Models Affected: BWC-2 & BWC-3

Air pressure and volume requirements for BWC-2 and BWC-3 units


Insufficient air volume will cause air pressure drop during wash cabinet operation. If the air pressure drops to less than 90 psi, performance of the BWC cabinet during unload and blow-off may be affected. Low air volume will result in incomplete battery blow-off. Acidic wash water remaining on the battery then runs from the battery onto the extractor, stands, and floor, leading to corrosion and damage. Insufficient air volume during the blow-off cycle may cause enough drop in air pressure that the wash cabinet door may close prematurely. This can result in damage to the battery or wash cabinet door.


The blow-off cycle requires 200 cfm for a 20 second cycle (67 cubic feet of air total). Each air cylinder has a 1.05 cubic feet displacement which translates into an additional 2.10 cubic feet of air required to raise the door of the cabinet. This means each cycle of the BWC-2 or BWC-3 will require 69 cubic feet of compressed air. To meet these requirements, BHS recommends at minimum a 10 HP compressor with a 35 cfm recovery on a 120 gallon tank. The air supply line from the tank to the wash cabinet must be 1" minimum with minimal use of elbows and tees to prevent additional pressure drop.


BHS offers an air compressor kit, part # BWC-ACK, which meets the minimum requirements for BWC operation.

*Note: This is rated for dedicated use with the BWC only. Any other demands to the air system will require appropriate upsizing based on additional requirements. It is recommended that the compressor be located within close proximity of BWC so as not to exceed 25 feet of air line to destination. 1” diameter lines are the minimum recommendation for sufficient volume for the blow off cycle. Any unit of smaller capacity may give unsatisfactory results.

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