Vilter compressor unloader valve

[duke717]

Hello all,
The other day I was checking the pressure switches on some Vilter 450 series compressors. All were six cylinders and all were gas unloaders. I had 2 machines that would not unload. The solenoid coils were energizing. These 2 machines had Hansen HS2 solenoid valves installed as the unloader valve. This is the first time I have seen this valve used for that. All of the other compressor unloader solenoid valves were the older type ( Alco I think ).
Is anyone using these valves and are they working properly? I am wondering if the valve is too small.
thanks

[McFranklin]

The Hansen HS2 has a 5/32" port and it is supposed to work on suction stop valves. The size of the valve wouldn't be my first choice for your problem. Especially if the machines have worked in the past. If the Hansen valves were just put in and it didn't work, then most likely they are the problem.
Do you have any other history on the machines?

[duke717]

According to the plant personnel, the valves were changed due to they were leaking ammonia.
When they replaced the valves, they did not check for proper operation. (they were replaced several years ago).
As far as machine history, these are older compressors and they tell me they have only had routine maintenence (oil and filters, clean strainers). No major work has been done on them.
Thanks

[duke717]

The plant is going to change out one solenoid to an S8F and and see if it will unload then.

[RANGER1]

The Parker (R/S) S8F should fit straight in.
Have you tried manual jacking spindle on Hansen if fitted ?

[Scott B]

The Alco valves have not been available for a while now and after trying several other valves (including the HS2) the Parker S8F with threaded flanges is still the best way to go, the biggest issue is the big bulky coil adding to the weight hanging on the thread. The HS2 will certainly be your problem especially if it is piped up with 1/4" tube. Good luck

[McFranklin]

The HS2 doesn't have a manual stem. It looks like a metal rectangle with a coil on top. I got busy at work today so I forgot to ask Vilter what valve they are using now. But I don't think the valve size is the problem. The unloader piston is less than 2" in diameter, and the machines sound like they are overdue for a top end overhaul at the very least.

[duke717]

Scott-- the tubing is 3/8"

McFranklin-- Yes, I am sure they are overdue for an overhaul. But you know how some plants are. They don't want to spend the money. I e-mailed vilter last week and have not heard anything yet.

Thanks for the help

[Scott B]

Hi Duke,
Even with 3/8 pipe the HS2 valve is too small for gas unloaders. Vilter now use oil unloaders as standard on the 450 series and as far as I know they will suggest s8f or the Hansen equivelant.
Scott

[duke717]

Thanks Scott, I think they need the bigger valve as well. I have not heard anything back from the plant yet. I probably won't. Until the next time I get sent over there to work on something else and ask them while I am there.

[JSakata]

Hello Everyone,
I work with fishing boats fitted with 448 and 458 NH3 compressors, all of them came from factory, fitted with Parker 04F25C6622CAF4C05,. 120V solenoid valves for unloading.
Its been aprox. 5 years since and now we have leaking problems with all these valves, Parker is no longer manufacturing these valves and offer no replacement or repair kits for them. I've also been looking for alternative replacements other than the bulky and heavy S8F that Vilter is suggesting to use. The problem is that in these installations the compressors are cramped in a small room, with no much space to allow the re-installation of these bulky valves with all the piping modification and supports needed to hold these in place without putting pressure on the tubing.
I've found that ASCO is about to release a new solenoid valve, especifically for NH3 application. Unfortunately they have been postponing the availabilty for more thant one month now. We are planning to try these on one compressor and see how it works.
The only worry that I have is the orifice size in these ASCO valves, seem to be too small.
Please take a look at the ASCO site (I can not post links yet) under catalog 35 Special Service Valves and let me know what you think.

Thanks
Josue

[Scott B]

Hi Josue,

The Asco valve looks very similar in size to the Parker valves that you are having trouble with. We too had problems with these valves and ended up fitting Parker S8f or Hansen HS8a. (the Hansen is more compact and looks neater of the two) These are 13mm port. The small Hansen valves (HS2 and HS6) are only 4 mm port and do not appear to work.
The ASCO valve with the 7.1 mm port would be certainly be worth trying when you can get them.
Cheers Scott