Question about Hill Compressor

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likkitysplyt

likkitysplyt

Member
May 26, 2017
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North Carolina, United States
I have heard it said many times that if you re-start your compressor with pressure in the line, that you can blow a fuse or fry a motherboard or break a piston etc, etc, etc. The general idea is that when restarting, make sure all the pressure is purged from the compressor in order to not put undue stress on the system causing breakdowns.

The Hill compressor shuts down at 75 degrees C and then re-starts when the temperature drops down to 67 degrees C. and will do it time and time again until it gets to the pressure you desire. 

How does the Hill not run into problems doing this, as each time it restarts it retains the pressure at which it shut down at and simply continues it's climb to the desired end pressure.

Just wondering???

Shalom

John
 
Sometimes whether you can do something and whether you should do something are very different.

With that said, I believe that Hill compressors are very well designed and engineered, by folks who know a lot more about compressors, design and engineering than I do.

But my personal 'bias' is that I won't re-start one of my own compressors when there is pressure in the line.

It is pretty common knowledge that a motor draws the highest current at start-up, when it is transitioning from zero RPM armature speed to (firstly) very slow speed (even if only for a short period of time), and then to it's 'running' speed. That is why many compressors have a couple of big capacitors in the AC supply, to reduce the 'hit' on the supply when the motor is asked to start spinning (turned on). I have seen compressors pop circuit breakers on start-up. Haven't seen any fried boards personally, but could definitely see how that could occur. Starting a motor with a load on it will only slow the process of transitioning from zero RPM to running speed, causing a longer period of high current draw.

On HPA compressors there should be valving in place which essentially isolates the pressure in the gun/bottle from the compressor to some extent. But I have seen in my own compressors where these valves get dirty and/or carbonized, and they stop working as they should. Once again, on a personal bias, I would never risk starting a compressor which I have purchased with my own cash, when there is pressure in the fill line. If everything is not working exactly as designed, you may end up breaking internal compressor components.

I think that the folks at Hill know their stuff, and know it a whole lot better than I do. But I also had very early issues with my EC-3000, and I no longer own one. Plus that model hasn't been available for all that long, so we don't have a lot of information on its reliability over time (although it is likely based on one of their other successful compressor designs which have shown long-term reliability, so this point may be moot).

Maybe I'm overly cautious with my equipment. But if that potentially reduces the need for rebuild, repair or replacement, that is just fine with me.
 
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If it was needed, one like me at least would assume the compressor would purge the air line, when it stop for temperature reasons, cuz if it dont in start up when colder with a line with pressure in it.

And in that case if they advise against not doing it manual, it do not "jive" with what the compressor do on its own, so not doing it manual can just be a means to minimize that load so it only happen when really needed.

I assume a automatic purge valve would add to the price, making it work with the control board i can not see as much of a challenge.



If temperature > xx deg C / shut down / open purge valve for 2 seconds / close purge valve

If temperature < xx deg C / start compressing again. ( never said i was any good at coding either ) 😁
 
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I think that the issue only applies to the cheaper Chinese pumps. Electric motors that need to start under load such as set duty cycle type reciprocating piston compressors have a two-speed starting process. Usually, it is just a simple centrifugal force shifting mechanism that shifts to 1-1 immediately when the motor spins up. My guess is that the lower quality units don't use this arrangement to keep costs as low as possible. I'm sure that your hill pump has been well designed to start and stop under load automatically and it won't cause any harm.
 
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Well, that is what the users manual says happens and it is designed to shut off at 76 degrees C and it never purges itself and then automatically starts up under a load until it gets to the pressure you designate. It does it multiple times if you are filling a bottle a nd never gives a problem. Of course I don't fill my 74 cu ft tank with it, I use an Omega Air Charger for that but if filling a Uragan bottle or an Impact bottle it may shut down 3 times depending on how high you want to fill it. Personally, I seldom go over 250 to 275 Bar, don't want to push it too hard, but so far it works like a dream. Thanks for all the input, You guys are great!

Shalom 

John
 
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