The upstream pressure (P1) enters the main valve body and passes through the piping to the pilot valve.The pilot valve is normally open, allowing the upstream pressure to move through the outlet port of the pilot valve to act on the bottom of the main valve diaphragm. This force pushes the stem upward, opening the main valve.As the downstream pressure rises to the setpoint, the pilot senses the rising pressure and begins to close. This throttles the flow to the main diaphragm. The pressure on the main valve diaphragm is bled off downstream and the main valve closes.In this way, the Mark 687 modulates between open and closed to maintain control.FeaturesSoft seat for ANSI Class VI ShutoffBalanced plug and piloted operation for extremely accurate regulationChoose from two pilot valves, 69L or 69H. These provide a variety of ranges, from 2-8 psi (0, 14-0,55 bar) to 70-150 psi (4,8-10,3 bar).
316SS / PTFE Trim is standard
Specifications
Sizes: 1-1/2″ (DN40) through 2″ (DN50)
End Connections
Threaded – FNPT, BSPT, BSPP
ANSI Flanges – 150#, 300#
DIN Flanges – PN 10/16, PN 25/40
Others available on request
Body Materials
Carbon Steel – ASME SA216 WCB
Stainless Steel – ASME SA351 CF8M
Trim Material: 316SS/PTFE (Standard on all valves)
Seat Material: 316SS /PTFE
Actuator Materials
Carbon Steel for WCB bodies
Electroless Nickel Plated Carbon Steel for CF8M bodies
Diaphragm Material: Buna-N
Service: Water, oil, gas, air and chemicals
Shutoff: ANSI Class VI
Available Spring Ranges
MK69L Low Pressure Pilot: 2-8 psi (0,14-0,55 bar), 5-30 psi (0,34-2,1 bar), 15-50 psi (1,0-3,5 bar)
MK69H High Pressure Pilot: 25-75 psi (1,7-5,2 bar), 70-150 psi (4,8-10,3 bar)
Minimum & Maximum Pressure Drop
Minimum: 25 psi (1,7 bar)
Maximum: 150 psi (10,3 bar)
Pressure Temperature Ratings: Maximum inlet 175 psi @ 100°F (12,1 bar @ 38°C); 175 psi @ 275°F (12,1 bar @ 38°C)
Flow Coefficients
1-1/2″ Valves: 45 Cv
2″ Valves: 45 Cv