R.G. Laurence Series 800

SERIES 800 are semi-Direct Operated valves suitable for air, steam, fuel gases, as well as light liquids at higher pressures than Series 700HP.

When the external lever is raised, a first-stage port opens, relieving the static line pressure on top of the main piston. A pressure inbalance is created because the first-stage port area is greater than the first-clearance areas feeding the top of the piston and this inbalance assists in lifting the piston off the seat to open the valve fully.

However, due to an auxiliary spring and a solid connection between the stem and the main poston in our valve, it is basically the raising of the lever, NOT this pressure assist, that provides a lifting action and thus, there is no dependance on a minimun pressure or flow to operate.