ChemTec Adjustable High Pressure Safety Excess Flow Valve Series HP-EFV-250-S

Features:

• Controlled bleeds resets automatically
• Field adjustable
• Positive shut-off option
• Materials: 316SS
• Maximum pressure 6000 psig
• Detects excess flows
• Detects increases in media viscosity
• Fuction: Restricts or shuts off flow
• Output: Switch contact

Applications:

CNG delivery

High pressure plant lines

Hydraulic systems

Operations:

Flow enters the unit and makes a right angle to the outlet port across the nose of a magnetic piston. The piston is held in place by attraction to an adjusting screw magnet. A pressure differential is created by flow across the piston. When the differential is great enough, the piston slides to a seat at the outlet port. The flow rate at which the piston actuates can be changed externally by turning the adjusting screw, thereby changing the piston's relationship with the flow stream.

In the auto reset model after actuation, the piston resets on a metal to metal seat that allows a controlled bleed. To reset the unit, pressure must be equalized on both sides of the piston. If the source is turned off, either upstream or downstream, the bleed will equalize the pressure and the valve will automatically reopen by magnetic repulsion from the fixed magnet located in the valve body.

For positive shut-off an elastomer is used on the nose of the piston. When it comes to rest on the seat it provides a bubble tight closure. To reopen the valve there are two options.
1. The upstream pipeline must be bled to atmosphere if the line downstream is at atmosphere.
2. A by-pass line with an on/off valve must be installed to port the upstream pressure to the downstream pipeline to equalize the pressure.

• Actuation ponts for air at 68°F and 14.7 psig
• Corrections must be used for other gases, line pressure and temperatures