Dema solenoid rebuild

[Don B.]

Does anyone rebuild their Dema solenoids?
I have several used Dema 414-p solenoids that I kept from my car wash rebuild, because I replaced all of these with new ones. I’ve never rebuilt one of these. I’ve always just replaced it with a new one when it went bad.
Just wondered if they hold up well after a rebuild kit? I noticed the kit doesn’t include the stem housing, just a new plunger and seat. I’ve taken several of these apart and noticed that it’s usually the plunger that’s worn. The square shoulders of the plunger are rounded off. I figured that’s what causes it not to open, or open all the way, because of drag. Not sure how long a new plunger would hold up unless you replace the stem housing as well.

 

[MEP001]

I don't rebuild the 412P or 414P. In my experience, once they start to not open all the way or not close, nothing seems to cure them completely. I don't use the 412P or 414P at all anymore after replacing a weep solenoid the day before a freeze, testing it several times to make sure it worked properly, then leaving, only to come back the next day to a frozen wash because it didn't open. I use 473P or 474P. They're more reliable, and a kit always gets them working properly again.

 

[Don B.]

I don't rebuild the 412P or 414P. In my experience, once they start to not open all the way or not close, nothing seems to cure them completely. I don't use the 412P or 414P at all anymore after replacing a weep solenoid the day before a freeze, testing it several times to make sure it worked properly, then leaving, only to come back the next day to a frozen wash because it didn't open. I use 473P or 474P. They're more reliable, and a kit always gets them working properly again.

Thanks. I’ve always had pretty decent luck with the 414 but like I said, I always just replace them instead of rebuild. Maybe I should eventually consider going to the 470 series!

 

[MEP001]

I refuse to use the 410 series anymore. They used to be much better and would last for decades. I've seen some on 50 year old D/H pump stands that have never been touched. Around 2000 they took a dump in quality and life span and they're junk now. I was still building equipment back then, and we were seeing only a few year lifespan. I switched to the 470 series and never looked back.

 

[Don B.]

Yep, a few years is about right on them. Probably switch to the 470 series as they need replacing. Should have done it when I replaced all of them during the rebuild!

 

[2Biz]

Dema 412 and 414 are piston actuated valves. When I bought my wash, it had a 414p on weep. It tested fine until the first freeze! It quickly made me do the research to learn they are not as trustworthy as a diaphram valve. I switched to an Asco diaphram valve and have never had a freeze up since. There are no Dema valves in my wash. All Asco or Kip.

 

[Don B.]

Dema 412 and 414 are piston actuated valves. When I bought my wash, it had a 414p on weep. It tested fine until the first freeze! It quickly made me do the research to learn they are not as trustworthy as a diaphram valve. I switched to an Asco diaphram valve and have never had a freeze up since. There are no Dema valves in my wash. All Asco or Kip.

I will probably switch the 414s over to diaphragm valves as they need replacing. I’ve been running these for about 20 years. I run 12 of them for 6 bays to feed my high-pressure pumps, as my pumps are pressure fed on both hot and cold side. I’ve had decent luck with them. I’ve never kept a record of how often I replace one, but it’s really not that often. Usually, when I have to replace one it’s because it won’t open, or open all the way. I’ve also always ran a Dema on my weep. Luckily, I’ve never had a problem with one freezing up my car wash. I have ran a few diaphragm valves over the years. I think they were GC valves. Never used Asco, but I use Kip on all my chemicals. But yeah, I think diaphragm valves are the way to go.

 

[MEP001]

I have seen Asco valves fail where there is a lot of flow through them because the valve body seat is bare brass. The DEMA 473P has a stainless seat and doesn't have that problem. Also the Asco kit costs more than an entire DEMA solenoid.

 

[Don B.]

I have seen Asco valves fail where there is a lot of flow through them because the valve body seat is bare brass. The DEMA 473P has a stainless seat and doesn't have that problem. Also the Asco kit costs more than an entire DEMA solenoid.

I do remember the GC diaphragm valves I used would wash out on the brass seats. Stainless would last a long time.