Air Solenoid Valves Allowed Inside An Electrical Enclosure?

[cowski]

I was visiting a competitor's shop and they showed me an electrical enclosure with air solenoid valves on the outside. They said something like "Yea since the code change we've had to mount all our valves on the outside..."

Does anyone know of any general code (NEC / UL508A / NFPA 79) that forbids mounting solenoid valves inside an electrical enclosure? Or any codes related to the pharmaceutical or food industry (CGMP, etc.)?

We tend to put our solenoids inside a stainless enclosure for sanitary reasons. Often there are a terminal blocks in these enclosures as well. Occasionally a few solenoids will share an enclosure with an entire PLC control sytstem... Is this allowed? We tube any exhaust ports from the valves to an exhaust bulkhead (rather than exhausting potentially moist / oily air inside the enclosure).

One thing I've noticed is there do not appear to be any NEMA 4X rated air bulkhead fittings on the market...right?

 

[cowski]

To add to my final though: There aren't any UL "Type" 4X air bulkhead fittings. I guess NEMA wouldn't be too interested in pneumatic products. Are there ratings for enclosure penetration products that don't pass wires?

 

[retirede]

I spent a good deal of my career designing control panels for air and gas compressors. It’s been almost 30 years ago, so things may have changed.
I’ve never known non-electrical firings to have any kind of UL or NEMA rating. We had a standard 1/4” NPT bulkhead fitting that was cad plated. We used it on everything except NEMA 7 control panels. There was a stainless steel version we used on occasion, depending on customer specs. The O.D. had a running thread that was a size that matched 1/2” conduit, so we used conduit sealing rings for NEMA 4 or 4X.

 

[petersonra]

You can use UL listed sealing washers for this.

 

[retirede]

You can use UL listed sealing washers for this.

Exactly!

 

[brycenesbitt]

I was visiting a competitor's shop and they showed me an electrical enclosure with air solenoid valves on the outside. They said something like "Yea since the code change we've had to mount all our valves on the outside..."
Does anyone know of any general code (NEC / UL508A / NFPA 79) that forbids mounting solenoid valves inside an electrical enclosure?

UL 508A has a rigid list of equipment you can use BUT it seems to apply only to the power components, not controls.
Are the solenoids line voltage or low power DC?

 

[petersonra]

UL 508A has a rigid list of equipment you can use BUT it seems to apply only to the power components, not controls.
Are the solenoids line voltage or low power DC?

It also applies to control components with a very few exceptions for devices in class 2 circuits.

 

[garbo]

Have wired in many panels the largest having 19 motor starters and never installed solenoids inside of panels that had relays, starters, timers, drives etc. Even if a solenoid that only handled air it sometimes has oil &/or moisture in the compressed air and could cause problems in the event of a leak. Like another post said have installed one or more solenoids in a dedicated box with at most a terminal strip for solenoid coils.

 

[infinity]

Don't most fire pump controllers have some sort of pressure controllers built in with the electrical components?

 

[brycenesbitt]

I was visiting a competitor's shop and they showed me an electrical enclosure with air solenoid valves on the outside. They said something like "Yea since the code change we've had to mount all our valves on the outside..." Does anyone know of any general code (NEC / UL508A / NFPA 79) that forbids mounting solenoid valves inside an electrical enclosure? We tend to put our solenoids inside a stainless enclosure for sanitary reasons. Often there are a terminal blocks in these enclosures as well. Occasionally a few solenoids will share an enclosure with an entire PLC control system... Is this allowed?

What type of air tube do the solenoids have? Could the competitor be reacting to a fire spread issue, with the tubes potentially melting?
Could you place the air valves behind a second "deadfront" like cover inside your enclosure, so a fire in the enclosure can't reach the tubes?

I'm trying to do something similar at https://forums.mikeholt.com/threads...-is-this-the-right-duck.2578308/#post-2887779
And finding UL508A to have been written with one very specific application in mind, not quite mine.

 

[Greentagger]

300.8 is close to what you are describing. But a j box is not a raceway.

 

[kwired]

Have wired in many panels the largest having 19 motor starters and never installed solenoids inside of panels that had relays, starters, timers, drives etc. Even if a solenoid that only handled air it sometimes has oil &/or moisture in the compressed air and could cause problems in the event of a leak. Like another post said have installed one or more solenoids in a dedicated box with at most a terminal strip for solenoid coils.

Been my experience. A place I work at has a rather large stainless enclosure that has mostly air solenoid valves mounted on the back wall, but over time has had timers or other electric components added, most of which is controlling at least one of said solenoid valves. Also has 30mm switches/pushbuttons mounted on the door that control not only solenoid valves but other items related to the process the valves go with.

Most everything inside this enclosure which has been in place for like 35+ years has a coating of oil on it from the various small air leaks that have occurred over the years.

 

[petersonra]

Mostly our customers require exhaust ports to be brought to the outside of the enclosure when a solenoid valve is located inside an enclosure so usually no issue with oil or moisture collecting from the valves.

 

[retirede]

Another option when we used with Asco Red-Hat valves was to remove the coil assembly and mount the valve by its stem through a hole on the bottom of the enclosure. Then reattach the coil assembly. The result is that the electrical connection is inside the panel, but all pneumatic connections are external. I looked for a picture, but don’t seem to have any.

 

[kwired]

Mostly our customers require exhaust ports to be brought to the outside of the enclosure when a solenoid valve is located inside an enclosure so usually no issue with oil or moisture collecting from the valves.

You never have leaks develop? In a noisy environment they don't get noticed very easily.

 

[retirede]

You never have leaks develop? In a noisy environment they don't get noticed very easily.

If you use nylon tubing, it will leak eventually. If you use stainless steel tubing with Swagelock fittings ($$$), you will likely never have a leak.

 

[petersonra]

You never have leaks develop? In a noisy environment they don't get noticed very easily.

Very rare. Even with plastic pushlok fittings.

 

[4-20mA]

Survey says... yes.
These are positive pressure purged boxes for a microfiltration unit.

This is for a DI Water system, similar set up.

Some areas the purged box has a pilot light on the enclosure door to indicate positive pressure/failure. If needed you could implement something like that. I will try to get a picture later for.

 

[kwired]

Survey says... yes.
These are positive pressure purged boxes for a microfiltration unit.

This is for a DI Water system, similar set up.

Some areas the purged box has a pilot light on the enclosure door to indicate positive pressure/failure. If needed you could implement something like that. I will try to get a picture later for.

Well those are enclosures commonly used for electrical. But in your application they are air solenoid enclosures and the only electrical in there with it is the supply conductors for the solenoids. Nothing electrical in there that is not directly associated with the solenoid valves, which I kind of assuming is what the OP is asking about.

 

[4-20mA]

Well those are enclosures commonly used for electrical. But in your application they are air solenoid enclosures and the only electrical in there with it is the supply conductors for the solenoids. Nothing electrical in there that is not directly associated with the solenoid valves, which I kind of assuming is what the OP is asking about.

Thanks, I see what you mean.