Protectoseal® has redesigned the Series 51700 Hinged Lever Arm Emergency Pressure Relief Manway.


Setting Ranges have been extended, the counterweight that determines the pressure relief set point is now positioned in a horizontal plane and is adjustable by adding or removing additional weights on the lever arm.

Series 52600 Combination Pressure/Vacuum Emergency Manhole Cover Vent has many new features that offer distinct advantages to our customers.


The minimum pressure relief setting has been decreased on all sizes in all materials of construction combinations.  The vacuum port opening has been increased in size to 12 inches in diameter from 8.5 inches, this feature significantly increased the vacuum flows.  The addition of a separate weatherhood for protection of the pressure and vacuum relief pallets and to preclude snow/ice from affecting the pressure relief setting.