Spirax Control Valve issue

[Luke_Mages]

I know this is a PLC site but it seems that many of you here have been in the industry a lot longer than I.

We have a pneumatically controlled 3" 1/4 spirax valve with a spirax bva200 series controller as the main supply control for 60psi steam. We've ruled out venting being an issue, but the valve doesn't close properly. We swapped out the vlave for a new one and it worked well for about a week and a half and then the same issue started again. We then swapped the pneumatic controller and the same result......

Any ideas?

 

[The Plc Kid]

What is the valves max closing PSI rated for?

 

[Luke_Mages]

150psi

 

[The Plc Kid]

You will need to break the problem down. Is your controller giving a fully closed signal? if yes then it would point to a mechanical issue in the valve if no then you will need to find out why the controller is not giving a full closed output when it should.

If the controller is not giving a full close output when it should then verify and possibly check calibration of it's input (PSI Sensor) and go from there.

Sound like it's just been parts swapping and not trouble shooting thus far.

 

[James Mcquade]

Is the valve rated for steam and the pressure you are operating at? The valve seals / bearings may be swelling or sticking.

what chemical(s) is in the steam?
is there any compressed air involved with the steam flow?

chemicals in the steam or in compressed air may be causing the valve to gum up, seals to swell or dissolve, bearings to become compromised and freeze up.

we had to replace about a 100 valves when a company got in a new air compressor and the compressor oil in the air lines caused the valves to quit working.

a food processing plant I worked for had a similar issue with chemicals.

regards,
james

 

[Luke_Mages]

So our distributor and spirax believe its a sizing issue. The customer had spec'd us 100psi when in fact we are at only 50 psi. This is increasing steam velocities to the point that they are damaging the valves and preventing them from properly functioning.

 

[The Plc Kid]

So our distributor and spirax believe its a sizing issue. The customer had spec'd us 100psi when in fact we are at only 50 psi. This is increasing steam velocities to the point that they are damaging the valves and preventing them from properly functioning.

I would find that theory a little difficult to swallow. I could not see the valve size be that much of difference on steam velocity. Sound like steam and mirrors.

 

[Luke_Mages]

I would find that theory a little difficult to swallow. I could not see the valve size be that much of difference on steam velocity. Sound like steam and mirrors.

we thought the same thing until getting that answer from three different sources and seeing the damage being done to the valve.

 

[The Plc Kid]

I stand corrected and have learned something new then.

 

[Luke_Mages]

I stand corrected and have learned something new then.

I've learned a ton from this....what a headache. All I did was write the program to control the system but somehow became the point man for running down this issue.

 

[dploof23]

I've learned a ton from this....what a headache. All I did was write the program to control the system but somehow became the point man for running down this issue.

Of course you did......you wrote the program right?


If your place is anything like mine, you own that puppy until it works perfectly.

Dave

 

[Luke_Mages]

Of course you did......you wrote the program right?


If your place is anything like mine, you own that puppy until it works perfectly.

Dave

Yep exactly.

 

[danw]

seeing the damage being done to the valve.

What is the damage being done to the valve? erosion of valve seat?

 

[The Plc Kid]

If your place is anything like mine, you own that puppy until it works perfectly.

And any other time it breaks and the problem is not Obvious or the Mechanic can's find it after 10 Minutes.

 

[dploof23]

And any other time it breaks and the problem is not Obvious or the Mechanic can's find it after 10 Minutes.

Your mechanics give it 10 minutes? You're lucky, mine will dig the hole deeper for a good half hour before turning over the original problem, and 3 more created during "troubleshooting", to me.

Dave