3 replies to this topic

[HnAw]

please i need info about forward velocity to close check valves wafer  dual disc, thanks at advance, same i need dP for reopen it

[fallah]

HnAn,

 

Appears you meant "forward velocity to open check valves..." or "reverse velocity to close check valves...".  Am i right?

Indeed, your required info about the velocity and dP are normally provided by relevant vendor... 

[HnAw]

fallah you're right thanks,

btw i'm trying model surge anticipating valves in AFT Fathom, but it doesnt show directly, pittifully Aft doesnt offer  support for clients with old version nor forum like intergraph does. i queted valve operation:

 

 

 

Surge- anticipating valve (code "RE")
The Dorot "RE" valve protects pumping system from the water hammer in the event of instant shut down of the pump (as caused by power failure).
The main valve is a direct sealing diaphragm valve, activated by two "Quick Response" pilots or by a battery- supplied electric command ("RE/EL" version). 
The valve is assembled as a Relief Valve on a tee junction downstream of the check valve, near the pump.  It opens instantly when the pump shuts-down, remaining open to relieve the returning high-pressure wave.
The valve closes slowly when the network pressure increases to the normal static pressure of the system.
The valve  also opens instantly when the network pressure exceeds the preset safe level and closes gradually when the network pressure returns to normal ("QR" function).
In effect the valve is a "Safety Fuse" for any pressurized system. 

i just only see vacuum breaker valve ( just gas /air)and relief valve (set positive pressure , no accept vaccum set point) or accumulator (it works but  it is not surge valve).

 

i tahnks you at advance

[Poosticks]

The forward velocity required to open a dual disc check valve will depend on the torque on the spring fitted - however it is probably in the range of 1.5 - 3.0 m/s.

 

The valve will not need any reverse velocity or back-pressure to close the valve as the spring should perform this function.

 

If you are modelling surge you will need the dynamic characteristic of the check valve (which describes the function of maximum reverse velocity passing back through the valve as the system deceleration increases). This will allow Joukowsky surge pressures to be calculated.

 

(The check valve manufacturer can provide this).

 

I would imagine with this information you can size the surge-anticipating valve and check its opening dynamics.