Catastrophic compressor failure...need info

[bsh3239]

I am working on assisting a company that suffered a compressor explosion in an ammonia refrigeration system. The reason: liquid ammonia made its way to the compressor. There are a number of compressors used for this system. In order to protect the remaining compressors, I am recommending that they install "traps" or drop legs before each compressor. The company is informing me that these compressors are already protected by the low pressure receiver/accumilator. I need to ask the group if this makes sense. My limited "engineering" understanding of ammonia systems - tells me that every system has to have a low pressure side accumilator - and this vessel(s) are typically located far from the compressors, so how would a low pressure receiver/accumilator be able to protect a compressor from liquid carry over? ANy insights might help me prevent another explosion and save some operators. Thanks in advance.
Seaturtle.........

[NH3LVR]

Welcome to the forum bsh3239!
The low pressure receiver/accumulator is between the equipment that could return liquid and the compressor. It should be equipped with a high level float that will turn off the compressors if a dangerous level is reached. A seperate trap is not required.
There are several ways a compressor can fill with liquid. Among them are no/bad discharge check valves, liquid from a discharge oil trap, and a leaking inter-stage liquid injection solenoid.
What people call an explosion is usually from a compressor filling with liquid from another source than the liquid line.
However this is general information. Without knowing the layout of your system it is difficult to offer specific advice.
If you can give us specifics the members will jump in and give you as much help as we can.
In your position I would consider calling in a NH3 contractor to evaluate the system and make specific recommendations. Industrial refrigeration systems require specialized knowledge of the components and safety issues. If a NH3 contractor is not available in the area consultants can be found who can come to
a plant and give you a opinion of what should be done.

[bsh3239]

Thanks for the quick reply. One more question: It is my understanding that the "safe" way to get liquid off of the wrong side of the compressor - is to use either another compressor to suck it off or use a portable "vacuum" to suck it off and return the liquid to the low side of the system. Is this correct. I understand that there are other ways to do the same thing - but I am focused on the "safe" way. This is why the compressor exploded - they got creative with getting the liquid off of the compressor - and they did not get it all. What is your opinion about adding heat to the system (i.e. blow torches to the pipes - to heat up the ammonia and return it to vapor state? Thanks for your time......

[US Iceman]

Did the compressor actually blow up as in: parts flying through the air?

The low pressure receiver should be sized sufficiently to store any reasonable amount of liquid volume while still allowing the liquid to separate from the vapor by gravity.

I have though seen liquid condense in a suction line and have the liquid run back to the compressors. I have also seen compressors flood-out with liquid for a number of reasons, but have never seen a compressor literally explode into many pieces. not saying it won't happen, but I have not seen it or heard about it yet.

The safest way to get liquid out of the compressor is to leave the sump heaters on, lock-out the compressor motor and leave the compressor set for a long period of time until the liquid evaporates.

This is why the compressor exploded - they got creative with getting the liquid off of the compressor - and they did not get it all

If the compressor really did explode the above makes me think they had a part of the compressor package isolated with cold liquid. And it's that which caused the explosion. That's very dangerous.

Sounds like these guys should not be working on ammonia systems?

BTW, i just posted this reply and noticed you placed several other posts in different areas. Please don't do that. It makes it more difficult to keep track of and dilutes your responses. And , it sorta looks like spam. Thanks.

[NH3LVR]

Thanks for the quick reply. One more question: It is my understanding that the "safe" way to get liquid off of the wrong side of the compressor - is to use either another compressor to suck it off or use a portable "vacuum" to suck it off and return the liquid to the low side of the system. Is this correct. I understand that there are other ways to do the same thing - but I am focused on the "safe" way. This is why the compressor exploded - they got creative with getting the liquid off of the compressor - and they did not get it all. What is your opinion about adding heat to the system (i.e. blow torches to the pipes - to heat up the ammonia and return it to vapor state? Thanks for your time......

Torchs are not very good for this sort of thing, A portable propane heater can be used. The safest way is to let it evaporate on its own. Of course if the compressor gets too cold it can fracture the water passages. This is a job for an experienced hand.
A recovery machine for NH3 (a "vacuum") is hard to come by in the United States.
A NH3 plant is best in the hands of an experienced operator. Quite often they are selected from a maintenance staff and given no knowledge of how the system works. A good operator has a passion for his craft.
I remember started up a 12 cylinder Carrier that I has rebuilt. We always monitored a startup for 2 hours just to be on the safe side. The operator came into the engine room and felt the suction and discharge. He then remarked "just like it should be, hot in and cold out" I was speechless.

A few years ago a accident happen at a cold storage near here. I did not see it but I talked to a serviceman who was there after the fact.
Apparently they had a Vilter piston compressor with the suction piped into the dischsarge of the engine room. The discharge of this machine went into a heat exchanger that provided underfloor heat.
As I understand it they had procedures to vent the machine before it was started. I am told this was not followed. Since the suction pressure was so high liquid condensed from the low side. When the machine was started it took the heads off.
This is my understanding of what happened. Again I was not there.
I would encourage a certain contributor to this site to contact you. He works as a consultant and can advise you. I believe you need a site visit to inspect the layout.

[aawood1]

Hi BSH3239, If you do not understand Ammonia systems go with NH3LVR and call in a specialized NH3 contractor. I have not seen a compressor actually blow up in 24 years working with Ammonia, Have seen the damage from liquid from the surge drum as we call it over here, e.g. discharge valves and piston damage in piston compressors and rotor and main bearing damage in screw compressors. For removing liquid go with USICEMAN one of the best for infomation on Ammonia.
Arthur.

[Grizzly]

Hi BSH3239, If you do not understand Ammonia systems go with NH3LVR and call in a specialized NH3 contractor. I have not seen a compressor actually blow up in 24 years working with Ammonia, Have seen the damage from liquid from the surge drum as we call it over here, e.g. discharge valves and piston damage in piston compressors and rotor and main bearing damage in screw compressors. For removing liquid go with USICEMAN one of the best for infomation on Ammonia.
Arthur.

Arthur.
I could not of put it better myself.
BSH3239.
There is a wealth of experienced guys on this forum from your side of the pond.
Please use them!
Your post frightens me somewhat.
You are honest enough to admit that you don't know enough. Good on you!
The bit I struggle with is the fact that you indicate that you are an "outside Adviser"
On a subject you do not know?
Am I right to be concerned?
Grizzly

[Magoo]

Bsh,
are you sure that it is liquid that has done the damage.
Heard of a similar effect recently when a suction check valve dropped a plate and screwed a screw big time,
an explosive result , once pulled down not a pretty sight.

[D.D.KORANNE]

1) another source of liquid in nh3 system is the lower than condensing temp of the circulating jacket water temperature . Water circuit should be switched off to the jacket through a solenoid valve .

2) oil separator during off cycle can also be a source of liquid back to compressor crank-case .

3) you may have an oil collector tank with a heater which boils off the liquid refrigerant & oil is supplied back to the compressor crank-case through a float .

4) as the liquid enters the hot cylinder during compression process , extremely high pressure generation occurs which can stall compressors , blast pistons in pieces , valve plates , top of pistons pick holes due to excessively high pressures. At times compressor can explode through head .
Valve reeds are susceptible to pressures due to incompressible liquid pressures but pressures generated in a cylinder through a large slug of liquid can result in ``explosion `` .

[bsh3239]

Wow - Thanks for all the replies. I will let the cat out of the bag, as I prompted a number of questions (sorry about that). I am an enforcement officer for a four letter agency that conducts Process Safety Management inspections (do not hate me...LOL). I inspect/investigate incidents in sooo many industries that I can not possible be an expert in all of them. So when I stated that I am advising - that means I am inspecting/investigating. I find these forums so very helpful to provide me with the real life applications and realities that the books can not provide. Some officers are too proud to ask the simple questions for fearing that they will appear stupid. I will never learn if I do not ask the questions - I feel that getting the opinions/insights for as many different sources - I then can provide a better service to the employees that I am asked to protect. With that out in the open - here are some additional facts:
1.) Yes, the compressor did explode - parts flying across the room - two operators standing in front of it when it "popped" - covered in ammonia - lucky to be here. Yes, it was liquid ammonia that caused it to fail - it was on the wrong side of the compressor and attempts to get the liquid off the compressor failed and upon start up the compressor failed.

So here are my trouble spots:
1.) Read a compressor manufacturer's manual and most of them require or heavily recommend a trap installed in line with the compressor. Almost every refrigeration system that I have dealt with has had to have a low pressure receiver - and yet the compressor manufacturer's still insist on a trap - Is it a good engineering practice to install traps seperate of the low pressure receiver for an additional level of protection for the compressors? What is the group's opinion. I could take the easy way out and tell this employer that they have to follow manufacuter's recommendations and that they need to install traps- however, I realize that there are consequences to systems if I were to make such a bold and "to the point" statement. I want to ensure I understand all sides before I make such a statement.
2.) If the low side (booster) compressors are suffering "slugs" is that a symptom that the low pressure receiver is under-sized? What would be the first thing to look at if the low side boosters are slugging?
3.) What is a normal frequency for compressor slugging? I realize it is going to happen - but how many times is getting to the point of too many? The answer may be that it is never acceptible - but give me your opinions.

I realize that it is not my job to design or inform the employer how their system may or may not be performing well. Technically my job is to audit their managment system of their equipment, so that they can ensure that their employees are safe (i.e. won't be by a compressor that fails). However, if I am able to gain a little more insight by chatting with you all, I may be able to provide better customer service to this employer and enhance my future endeavors in refrigeration plants. My end goal is to see if there is something "big" that this employer is missing (regarding their compressors and the fact that ammonia is making its way to the compressors). I know it can be complicated - with a million explainations as to why - but regardles of the reason - would the installation of a trap, level indicators and cut-outs be the appropriate fail safe measure?
I thank you all for your time and insights. Good Evening
Seaturtle.....

[US Iceman]

1.) Read a compressor manufacturer's manual and most of them require or heavily recommend a trap installed in line with the compressor. Almost every refrigeration system that I have dealt with has had to have a low pressure receiver - and yet the compressor manufacturer's still insist on a trap - Is it a good engineering practice to install traps seperate of the low pressure receiver for an additional level of protection for the compressors? What is the group's opinion. I could take the easy way out and tell this employer that they have to follow manufacuter's recommendations and that they need to install traps- however, I realize that there are consequences to systems if I were to make such a bold and "to the point" statement. I want to ensure I understand all sides before I make such a statement.

What they typically refer to as a trap is not a pipe trap, but what is called a suction trap. This is the same thing as a suction accumulator or low-pressure receiver. The lingo in this trade is something like the joke of Great Britain and the US being separated by a common language. Some systems have a lot of different configurations that dictate how that suction trap is also configured or designed.

2.) If the low side (booster) compressors are suffering "slugs" is that a symptom that the low pressure receiver is under-sized?

Could be. Or, it could be caused by something else. It doesn't matter if it's a high-stage or low-stage compressor. Contrary to popular opinion, size is not the only thing that matters. it might be how the system is operated also.

3.) What is a normal frequency for compressor slugging?

Absolutely zero. nada, zilch. Slugging is not normal and should not be accepted.

Without meaning to start a border war, how do PSM audits involve design reviews? The system should have gone through a HAZOP study, so if they missed something I could see how it would impact Hazardous Operations however...

[bsh3239]

To answer the question regarding PSM and design evaluations - you are correct we do not evaluate designs. The one thing that is expected of us is to ensure that the system is designed to good engineering practices (plain english - we read A LOT of standards - very exciting...). Thus if we find something that does not comply with design standards (e.g. ASME boiler/pressure vessels, API - american petroleum industry bulletins, etc) we have to require the employer to bring the system up to standard. A perfect example of this in ammonia refrigeration rooms is: IIAR and RETA all state that it is a good engineering practice to have quick stopping valves on oil drain pipes - we often find regular valves on these drain lines. We then site the industry recommendation and require the employer to install them. That is what I was attempting to get at by my messages - are additional traps really required outside of the LP accumilators - I REALLY appreciated the explaination that a trap is also referred to as the accumilator. When you are not in the business - it is hard to learn the Jargon on the fly. If the forum and the IIARs and RETAs would have told me that YES, it is a good engineering practice - and I determine they were missing from the system, then we would ask the employer to install them. I found this last post very helpful. Thank-you.

[Sridhar1312]

Normally moment liqud traces comes in the compressor noise amperage does give indication.
Normally experienced technician should be able to assess this and take preventive action.
Crankcase heater can also help to some extent as long as it is programmed to be on whenever the temperature goes low as is the case when liquid gets in.
Most important aspect if the balanced system if liquid comes there is a flaw in the system functioning, which again experienced technician will be able gauge.
In my 33 years experience have heard of releief valve some times blowing up due to pressure build up.
Even over charging will cause higher suction and higher discharge which may be the cause. But even then the safety relief valve should precede breaking of cylinders piston etc.
If the compressor has blown it must be due to high pressure as the casing of the compressors are not as high as the receiver.

[Grizzly]

Wow - Thanks for all the replies. I will let the cat out of the bag, as I prompted a number of questions (sorry about that). I am an enforcement officer for a four letter agency that conducts Process Safety Management inspections (do not hate me...LOL). I inspect/investigate incidents in sooo many industries that I can not possible be an expert in all of them. So when I stated that I am advising - that means I am inspecting/investigating. I find these forums so very helpful to provide me with the real life applications and realities that the books can not provide. Some officers are too proud to ask the simple questions for fearing that they will appear stupid. I will never learn if I do not ask the questions - I feel that getting the opinions/insights for as many different sources - I then can provide a better service to the employees that I am asked to protect. With that out in the open - here are some additional facts:
1.) Yes, the compressor did explode - parts flying across the room - two operators standing in front of it when it "popped" - covered in ammonia - lucky to be here. Yes, it was liquid ammonia that caused it to fail - it was on the wrong side of the compressor and attempts to get the liquid off the compressor failed and upon start up the compressor failed.

So here are my trouble spots:
1.) Read a compressor manufacturer's manual and most of them require or heavily recommend a trap installed in line with the compressor. Almost every refrigeration system that I have dealt with has had to have a low pressure receiver - and yet the compressor manufacturer's still insist on a trap - Is it a good engineering practice to install traps seperate of the low pressure receiver for an additional level of protection for the compressors? What is the group's opinion. I could take the easy way out and tell this employer that they have to follow manufacuter's recommendations and that they need to install traps- however, I realize that there are consequences to systems if I were to make such a bold and "to the point" statement. I want to ensure I understand all sides before I make such a statement.
2.) If the low side (booster) compressors are suffering "slugs" is that a symptom that the low pressure receiver is under-sized? What would be the first thing to look at if the low side boosters are slugging?
3.) What is a normal frequency for compressor slugging? I realize it is going to happen - but how many times is getting to the point of too many? The answer may be that it is never acceptible - but give me your opinions.

I realize that it is not my job to design or inform the employer how their system may or may not be performing well. Technically my job is to audit their managment system of their equipment, so that they can ensure that their employees are safe (i.e. won't be by a compressor that fails). However, if I am able to gain a little more insight by chatting with you all, I may be able to provide better customer service to this employer and enhance my future endeavors in refrigeration plants. My end goal is to see if there is something "big" that this employer is missing (regarding their compressors and the fact that ammonia is making its way to the compressors). I know it can be complicated - with a million explainations as to why - but regardles of the reason - would the installation of a trap, level indicators and cut-outs be the appropriate fail safe measure?
I thank you all for your time and insights. Good Evening
Seaturtle.....

Erm!

Yes, it was liquid ammonia that caused it to fail - it was on the wrong side of the compressor

So which side of the Compressor was the liquid?
If it was discharge side?
Your comment does not make sence related to what you have told us so far!
Then a trap is irrelevant.
What we need to establish is what caused the liquid carry over in the first place?
Then how it was dealt with when it occurred.
I doubt whether plant design will be the real culprit.
I still think it would pay to enlist the assistance of one of our American Colleagues.
I have to ask why did the operatives turn it on?
How did they determine that there was liquid there and when it had gone?
Grizzly

[Superfridge]

Do not install a trap or drop leg before the compressor if the system allready has a accumulator/LP separator/LP pot/suction trap/LP reciever ect. .

The pipe between the LP seporator and the compressor is known as the "dry suction" line. Dry gas only.

Tell us more about the system if you could. Sorting out refrigeration problems is what fridgys live for.

[US Iceman]

If the forum and the IIARs and RETAs would have told me that YES, it is a good engineering practice...

Sometimes what gets passed around as good engineering practice is dependent upon the individual doing the engineering practice. This can be as far fetched as "that's the way we have always done it and it worked" also.

The main issue I have with this type of logic is that repeated enough times it becomes construed to be good accepted engineering practice. Sort of like a rumor gaining credibility or repeated enough times where it becomes believable.

I understand the position you are in. Coming in from the outside and trying to enforce regulations in a field such as this can be a daunting and thankless task.

Especially when you are faced with the logic of: My refrigerant inventory is 9,990 lbs so I don't have to comply with 1910.111. General Duty clause what's that?

PS. You are welcome. If the industry did a better job of helping the auditors the systems would improve. An adversarial relationship does no one any good.

[desA]

A good consultant will he worth his/her weight in gold (the USD is now only paper value

[US Iceman]

A good consultant will he worth his/her weight in gold (the USD is now only paper value

Being paid in gold is good. Double eagles or Kruggerands is OK too.

[bsh3239]

You guys (gals too) have been Great - Thanks so much. You have assited me to not get bogged down in the "trap" issue and I have been able to return to the facility and ask some more very pertinent questions and field verify some additional facts. I wish there were these types of forums available to me when I am dealing with chlorine gas plants, formaldehyde generators, etc. It is just nice to be able to ask questions of people neutral to the situation at hand. I am certain I will return at some point with more situations and questions (we have alot of refrigerated spaces....)
THANKS AGAIN.

[RANGER1]

Makes you wonder if they are using a level probe without hard wired high level switch to stop compressers .

[bsh3239]

Makes you wonder if they are using a level probe without hard wired high level switch to stop compressers .

Because of the forum/group I was provided with some pertinent info. I went back and I did verify that the low pressure receiver was equipped with a high and low level float. These float switches are connected to magnetic level indicators - that in turn will trigger a cut out and shut down the compressors - which in turn will shut down the entire system.

Hey I just thought of another question that your group probabily has an opinion about:

How much ice build-up is too much build-up? I have been using the rather arbitrary number of an inch of ice or more is getting excessive. Please feel comfortable to disagree with this number...Thanks again

[US Iceman]

How much ice build-up is too much build-up?

Where?

On piping with insulation you should never have ice. Ice on insulated pipe shows a failure of the insulation & vapor retarder. Ice on some control or service valves is not a big deal, since these are not usually insulated to allow for easier service.

If a low temperature pipe stays at that low temperature constantly the ice only increases the dead-weight on the pipe and increases the heat load due to parasitic heat gain. If the pipe is cycling through temperatures like a hot gas defrost line will the repeated freeze-thaw cycle can promote increased corrosion rates, if the vapor retarder has failed (and most will or have). Corrosion is the main issue the way I see it.

[bsh3239]

Where?

On piping with insulation you should never have ice. Ice on insulated pipe shows a failure of the insulation & vapor retarder. Ice on some control or service valves is not a big deal, since these are not usually insulated to allow for easier service.

If a low temperature pipe stays at that low temperature constantly the ice only increases the dead-weight on the pipe and increases the heat load due to parasitic heat gain. If the pipe is cycling through temperatures like a hot gas defrost line will the repeated freeze-thaw cycle can promote increased corrosion rates, if the vapor retarder has failed (and most will or have). Corrosion is the main issue the way I see it.

Insulation - that is a given - I always look for water migration into the insulation (vapor barrier leaks). The lesser known stuff is: Pumps - when the pump is completely covered in a thick layer of ice, when an uninsulated line is covered in a layer of ice....In general with these cases - I have been starting to address the ice issue - when there is about an inch depth of ice build - up - mainly due to the added weight of the ice over the system. I will address the valve issue when the ice has completely encased the valve stem - I have even found valves completely encased (stem and handle) in ice. These are no- brainers. The harder cases to evaluate are the pumps and uninsulated lines. I have tried many times to locate literature that would provide guidance on an acceptable level of ice build-up on such items - but I have not been successful.

[US Iceman]

Ice is a fact of life in low temperature systems. Exposed valves will accumulate it, but your suggestion of the ice covering the valve stem is an issue. If you need to close the valve and can''t, that's an issue.

ice on pumps I would not worry about though.

[Segei]

Because of the forum/group I was provided with some pertinent info. I went back and I did verify that the low pressure receiver was equipped with a high and low level float. These float switches are connected to magnetic level indicators - that in turn will trigger a cut out and shut down the compressors - which in turn will shut down the entire system.

Hey I just thought of another question that your group probabily has an opinion about:

How much ice build-up is too much build-up? I have been using the rather arbitrary number of an inch of ice or more is getting excessive. Please feel comfortable to disagree with this number...Thanks again

I don't think that low level should shut off the plant. Low level should shut off the pumps.

[RANGER1]

Felt like having a rant as computer has been down for a week .
Obviously this client have some serious problems .
If you have high level switch it should shut down plant well before compressors get any liquid .Normally have 5-10 sec delay for nuisance trips .
Hopefully high level switch works and is at right height on vessel .
Sometimes depending on piprwork plant could shutdown and level can increase in accumulator because wet return pipework has "X" amount of liquid in it .
In this case you could continue to run liquid pumps to prevent it ie keep circulating it .
Dry suction header to compressors preferably should also have slight fall back to accumulator so it can help drain it if something bad happens .
Elbow facing up in vessel on dry suction usually have a 1/2" hole in bottom for liquid to drain back out of header .
In general most high level in a plants that has worked OK are usually oil related or make up solonoid leaking .

If oil gets into control column area it slows reading down as liquid ammonia can't get past it to register on float switches etc .
Have heard on one occation that a vessel was piped up in reverse ie wet return /dry suction mixed up .
All above is really only related to liquid entering compessor suction or interstage suction .
Rant over .

[aawood1]

Hi Bsh3239, At this time I'm pumping out and shutting down a 30 + year old Ammonia system and as for ice build up a lot of the liquid line valves have to have the ice chipped away to find the valve spindles. As USIceman has put it Ice is a fact of life in -42oC systems. We have removed lagging from some of the pipework after it's had the liquid and gas removed from that section and it's then taken 3 to 4 days for the ice build up to fall off. And yes we did heat up the oil to boil off the liquid ammonia in it before draining off the oil from the pipework. I have seen liquid pumps with so much ice build up on them that you can not make out what type of pump it is or what make. Only two more moves to make with the ammonia and it's around 20 tons in to the recovery tankers and the system is empty and dead. ( sad day one more old ammonia system gone)
Arthur.

[Grizzly]

Hi Bsh3239, At this time I'm pumping out and shutting down a 30 + year old Ammonia system and as for ice build up a lot of the liquid line valves have to have the ice chipped away to find the valve spindles. As USIceman has put it Ice is a fact of life in -42oC systems. We have removed lagging from some of the pipework after it's had the liquid and gas removed from that section and it's then taken 3 to 4 days for the ice build up to fall off. And yes we did heat up the oil to boil off the liquid ammonia in it before draining off the oil from the pipework. I have seen liquid pumps with so much ice build up on them that you can not make out what type of pump it is or what make. Only two more moves to make with the ammonia and it's around 20 tons in to the recovery tankers and the system is empty and dead. ( sad day one more old ammonia system gone)
Arthur.

Indeed a sad day.
Surprisingly there are new systems being installed.
It's slow I know.
But if only more people would learn how Good and energy efficient Ammonia is!
I suspect there would be more.
(Good point about the ice build up on liquid pumps-been there myself, many times).
20 tons Imperial! Thats a fair sized system.
Cheers Grizzly

[aawood1]

Indeed a sad day.
Surprisingly there are new systems being installed.
It's slow I know.
But if only more people would learn how Good and energy efficient Ammonia is!
I suspect there would be more.
(Good point about the ice build up on liquid pumps-been there myself, many times).
20 tons Imperial! Thats a fair sized system.
Cheers Grizzly

Hi Grizzly, As you say a sad day for this one but's it's being replaced with a new plant rated at 1.2 mega wats system with a smaller Ammonia charge some where around 4.5 tons. On the connections in to the old freezer headers we had around 400 to 600mm of ice build up along the empty new pipe work and upto 20 mm thick in only 14 days on the wet return's.
Arthur
Arthur

[alan wolf]

hello
I have read this thread with interest and had experience before 1970 of a Also agree safeties high accumulator level stops compressor and low stops pumps.

Joined a freezer ship in 1970 and u could not get in brine room for ice, took some time with water hoses to see what was in there.

My other comment is down to service and maintenance and whether oil was responsible not being drained regularly. Had a plant where all dran valves were badly coroded and finally got them changed. Took a lot of oil out of evaps.

Would of liked some better info on the plant in question.

Any ammonia leak can then lead to explosions depending on volume in air.

regards
alan

[alan wolf]

second quote
I had a compressor faulure piston went thru head of an old Sternes NH3 compressor which made it a write off.
Bottom end failed. This was at an Ice rink and compressor driven by a water wheel. They could not get in to stop it initially.
alan