clean hole in diaphram
I have a general question for the brewers out there.
I currently am using ASCO Red Hat solenoids to control the flow of glycol to my jacketed fermenters. I am using a 24V coil version. I have had problems intermittently with valves not completely closing during a fermentation causing the tank to be chilled too cold, interupting fermentation. One culprit I have found was some PVC glue the plumber, who repaired the system with, left in the line. I have added an inline filter now to catch debris.
Are there any reccomendations for alternative 24V solenoid valves? Any input would be geatly appreciated.
clean hole in diaphram
I would watch out for pieces of pvc from cutting the pipe more than anything else. If you installed a trap filter, that should take care of most of those. We used the same solenoids at Lost Coast for the time I was there (off and on from '81 to 2002) without any real problems, although you might want to keep an extra solenoid handy in case the body, coil or actuator go bad. A couple of extra sensors would also be useful. It's electrical, which means it can go at any time, not on a regular schedule. Think back to any cranky car you've had.
Installing extra ball valves can save you glycol in case of repair, but you can lose just as much or more in installation. We also had bypass portions, but with later copper installs we went without. Currently have had no problems with the system I work on (knock on wood) and it has similar solenoids. At LCB we also installed a pressure demand switch with a power inverter to save money. Paid for itself in a few months. Call Bill and see if he can help.
Not knowing much specific about solenoid valves, I can offer some info regarding control valves from oil and gas plant/refinery installations!!!
Control valves are not supposed to be used as 'tight shutoff valves', and it is normal to install ball valves for this purpose. When not in service, the ball valves should be closed and the solenoid de-energised (i.e. allowed to return to its fail-safe position, which I assume is closed in this instance) to prevent wear on the trims and seats of the control valve.
There are many things which can cause control valves to leak:
1. Not designed to be 'tight shutoff' (as above)
2. Worn trim
3. Worn seat
4. Actuator not physically able to close the valve fully (looseness in fitting of shaft etc.)
6. Valve chatter (i.e. minute fluctiations in on/off signal continuously energising/de-energising the actuator when supposedly in the 'closed' position)
... to name a few.
Don't know if this info will help in this case, but in general it would be good to make use of ball valves and filters upstream of the solenoids. Retrofit them it you can.
Steve, I believe these valves are "pilot operated" which means they open and close via a spring assist diaphragm. A tiny hole that the solenoid proper opens equalizes pressure across the diaphragm, allowing the spring force to open the valve. (Assuming energize to open) This hole is subject to plugging. If a piece of plastic/teflon tape/metal shaving/etc gets lodged in the hole, the valve will not close. If it blocks the hole completely, the valve will not open. It is also possible that you have something similar to the 8210 series which also uses a small orifice to equalize pressure across a diaphragm. Same gig. My installations use pressure reducing valves and have isolation ball valves on each side of the solenoid valve/pressure reducing valves to facilitate repair. I have found some pressure reducing valves that have a small cylindrical screen strainers on them that work great for preventing this sort of problem. I also install a fine mesh strainer in the main glycol line just to keep from cleaning many individual strainers frequently. The ASCO red hat line is a good brand--believe it is industry standard. Here's a link to ASCOs Red Hat 8210 line which is common in this application. http://www.ascovalvenet.com/pdf/Lite...210_8.13R1.pdf
I wouldn't change. I think that your solution of a filter/strainer will correct the problem. Hope this helps. Good luck!
Many thanks for the thoughtful responses. I never really understood the importance of the diapfram hole in equalizing pressure in valve. Looks like the current valves will stay and the filters will get finer. Thanks again, Steve
I'm having similar concerns and am looking to install some particulate protection. How fine a screen/filter are people using, and what style? Nylon T strainers? Inline bronze "Y"?