A vacuum valve is an inexpensive form of insurance against water intrusion in an engine, which could lead to expensive repairs. The maximum ambient temperature should not exceed 60 ºC (140ºF). The valve opens at a pressure which is equivalent to 30-50mm (7.47-12.45 mbar) Water Column. The materials used are resistant to sea water, fresh water and to glycol compounds in appropriate concentrations. Avoid exposing the valve to oil and grease. If it has been in contact with such substances, please clean or replace it.