API Plan 72 Support For Dry-Running Seal

[HoustonMechEngr]

My seal vendor has provided me a copy of a proposed control panel in support of a dry-running secondary seal to use nitrogen as the "buffer" gas.

I noticed on the drawing that the order of instrumentation on the supply leg is as follows:

Filter - Pressure Regulator - Pressure Gauge - Flow Meter - Needle Valve

I have heard mixed responses on where the needle valve should be placed. Should it be upstream/downstream of the flow meter and pressure gauge. The seal vendor has advised that the needle valve should be placed after all instrumentation, but then you have no means of measuring the pressure/flow downstream of the needle valve. Am I thinking bakwards here? Thoughts?

 

[Hidromar]

hummmm..... is this a "seal-vendor", or is he introducing their "brand new filter's catalogue"?

Regards from a "seal vendor" ;-)

http://www.hidromar.es

 

[JJPellin]

The standard drawing from John Crane for an API Plan 72 shows needle valve then flow meter.

Johnny Pellin

 

[flexibox]

The needle valve should be upstream as mentioned in JJPellins response. In the event of an operator isolating the valve it will show what is at the seal.

Hidromar How about a constructive reply to the questions?

 

[HoustonMechEngr]

JJ and flexibox,

Thanks for the response. That has always been my preferred approach to regulation and metering of the low pressure nitrogen purge and when my contact advised opposite it certainly surprised me.

 

[Hidromar]

Touché, flexibox!

Sorry about to be sarcastic, I'll try to do my best for future!

http://www.hidromar.es