Proper venting of polyethylene chemical storage tanks is vital for safe operation. It is also critical to maximizing a polyethylene storage tank's effective lifecycle. Poly chemical storage tanks are designed to function at atmospheric pressure per ASTM-D 1998, the industry standard for producing vertical polyethylene chemical tanks. During pneumatic offloading from a tanker truck, offloading pressures can exceed 30 psi, resulting in high ACFM rates. Under this scenario, standard venting designs are inadequate to release the pressure. To protect against an over pressurized chemical storage tank you should consider one of our innovative tank vent lid solutions.
Under this scenario, standard venting designs are inadequate to release the pressure. To protect against an over pressurized chemical storage tank you should consider one of our innovative tank vent lid solutions.
Poly Processing offers two tank lids to alleviate chemical storage tank pressure: The SAFE-SURGE®manway cover and the F.S. 2650® manway tank lid cover. Let’s look at the chemical storage situations that determine the use of these two lids.
SAFE-SURGE® Manway Cover Chemical Storage Tank Lid
The SAFE-SURGE® is an emergency pressure release lid designed specifically for pneumatic-filled tanks, and is ideal for tanks located indoors when standard venting that is designed to evacuate fumes outside the building. The SAFE-SURGE® lid is designed only to come into play during an event that could damage the polyethylene tank. It works by actuating a weighted lid on a swing arm when air pressure surges beyond .25 PSI and the primary vent can no longer adequately handle the ACFM rate. This ensures atmospheric pressure is maintained at all times.
While the tank is equipped with its own vent fitting, the SAFE-SURGE® chemical storage tank lid provides that added level of safety required for all pneumatically-filled indoor tanks without scrubbers.
For tank venting specifics, please refer to these tank venting requirements.
F.S. 2650® Manway Cover Chemical Storage Tank Lid
For chemical storage tanks located outdoors where fumes are not a concern, the F.S. 2650® Manway Cover is the less expensive option for safely handling any air pressure surges. This combines a vent and manway cover into one engineered lid system that can evacuate air volumes up to 2650 ACFM, which is well within the calculated maximum potential pressure surges resulting using both 2 and 3 inch fill lines (maximum ACFM from a 2 inch standard line is 910; and 1150 from a 3 inch line).
When fumes can be vented safely on outdoor chemical storage tanks without causing damage to the environment or injury to workers and the public, the F.S. 2650® Manway Cover saves money since additional tank vent fitting is not required.
Finally, bolted fume-tight manway covers are available for chemical storage tanks containing highly toxic, dangerous chemicals such as hydrochloric acid or acetic acid. In the event a scrubber is necessary on the storage tank, the fume-tight lid ensures that no fumes will be emitted from the tank.