Hall HSO 6231

[Tycho]

Greetings

Anyone here that has any "exploded view" or cutaway drawings of this compressor?

I have the installation & operation manual, but I don't have any drawings.

Been 25 years since I last saw a Hall mono screw and that was a small HS2020 or something.


Better yet if anyone has operated one, I'm having some issues with a brand new plant.

RSW system with on demand oil pump.

OP sensor is mounted on the side of the compressor and whenever the oil pump starts, the pressure on this sensor starts oscillating between 7-15 bar, however the sensor on the pump outlet (OPF, between oil pump and oil filter) is dead stable.

The pump is on demand, because it's OP minus LP, so once it gets load the differential pressure is enough.

https://youtu.be/EVQIr8Gt4Ys

I'm left with the suspicion that there may be either an internal non return valve on the oil port, or the compressor is somehow flooded with oil and gulping it out, kinda like an Howden XRV at 2000rpm where it's basically an oil pump

Amps and KW readings are dead stable too.

any and all input would be greatly appreciated

[seanf]

Do you get the same readings if you put a gauge onto where the OP sensor on the comp is?

Is the video of it running at a fixed capacity, or is it loading up?

Is it a Halls system, or just a Halls comp?

What cooling does it have? Liquid injection, oil injection .....

[Tycho]

Do you get the same readings if you put a gauge onto where the OP sensor on the comp is?

Is the video of it running at a fixed capacity, or is it loading up?

Is it a Halls system, or just a Halls comp?

What cooling does it have? Liquid injection, oil injection .....

The video is showing the startup, compressor starts at 44% slide load as per Hall, HP minus LP difference is to low to provide diff.oil pressure, so the on demand oil pump kicks in to provide lube oil pressure.


It's a Hall compressor, skid is built by SES, PLC control system is our own
in house.



Obviously oil injection into the compressor, but Discharge/oil cooling is Liquid refrigerant injection.

The LRI is two AKVA 15-1 valves that are controlled by a PID in the PLC, and they only kick in once the HT (high temp/discharge temp) is above 55 or 65°C

Haven't seen the settings... but personally I cringe a bit if the discharge temp is below 65°C


Hall and SES seem to be focused on that there is something wrong with the "oil pressure overflow valve" or with the internal valve in the oil pump...

[Tycho]

Do you get the same readings if you put a gauge onto where the OP sensor on the comp is?

I'm driving there on monday to go hands on.
(8 hour drive, may be 10-14 hours, depending on how often I get trapped behind mobile homes of people that have aaaaaaall the time in the world)


We have remote access on all our systems, last one I helped were like shown on the map...
Found out it was a bad relay by playing around with the system.

If I'd had to fly up there, it would have cost the client $2000 in plane tickets alone, then my billable hours...

[RANGER1]

Tycho,
Sorry only gave hard copy, sent a few pictures to your Gmail, not sure if relevant.
I would take a new transducer & a few gauges to verify transducers, change oil filter, check oil level.
Oil pressure after pump suspicious, being so stable.
Does pump have a filter on suction side, if so check.

[seanf]

Be interesting to hear what you find.

[cricri]

We had a similar kind of troubles on Grasso V piston compressors.
instable oil pressure depending from running speed.
after many try ( many years) the best way to solve that is to had a dampering orifice on the pressure sensor (for us AKS3000, already tapped, added a screw with a small hole). This is now a referenced spare part from Danfoss.
The other way is to had a length of pipe between compressor and sensor.
V compressors have sensors fitted to the compressor casing and length between oil pump and sensor is very short.
in your case, rotor pass at the oil injection can create a pulse and distort the mesurement. excessive oil injection can be an other way.
As suggested before, check with a gauge to compare

[Grizzly]

sound knowledgeable advise , You cannot get any better.
well done cricri

[RANGER1]

Discharge & oil temperature also seem very low, 7.4 bar about 20 deg C for ammonia, with discharge & oil temperature 30 deg C.
Most liquid injection always minimum 50-55 deg C to keep oil clear of refrigerant.
Maybe more thann one problem.

[Tycho]

Tycho,
Sorry only gave hard copy, sent a few pictures to your Gmail, not sure if relevant.
I would take a new transducer & a few gauges to verify transducers, change oil filter, check oil level.
Oil pressure after pump suspicious, being so stable.
Does pump have a filter on suction side, if so check.

Thanks Ranger, I have that manual, but not the drawings you attached, still waiting for a paper package from Hall.

I'm bringing a box of goodies, it's a long drive so wouldn't want to end up without any spares

There's a strainer on the pump suction., going to have to take start there and work my way forward

[seanf]

More of a daft question than anything useful but,

If youve got a screw comp on a system with a low suction to discharge pressure difference. Could you have a point along the compressors screw(s) where the gas pressure ends up higher than the oil pressure at the rotor oil supply ports?
Maybe only when the oil supply has a restriction?

[RANGER1]

Had a plant room with two of these type machines, same duty, 100 % loaded.
Machines were relatively new, like a few years old, one had more ice on suction than the other.
Turns out they have an internal check valve (ball bearing) that allows oil to drain out of machine, back into oil separator when off.
This can occur if oil pump runs & fails to start a few times.
Turns out ball bearing went AWOL causing massive internal bypass.
Apparently common 20 years ago.
Oil pump also not performing, got a new one with great difficulty (Viking 4LEV or something like that , 10 l/m)
Nice to have one of those as well on a big trip!

[cricri]

Some illustration of this issue. Sampling rate 1second.
V-oil-press.JPG

[Tycho]

Ok, so I'm back home from the site.

First thing I did was to fire up the plant so I could watch and listen to what it was doing, instead of just quietly watching it on my computer.

There were no weird sounds or vibrations and it behaved exactly like before, oil pressure after the oil filter was wildly going up and down.

There is a Hansen valve that by-passes from pump discharge to pump suction, and I tried adjusting the by-pass pressure without getting much of a result, I let it all the way down and all the way up and it still seemed to have the same pressure on the pump outlet.

hmmmm

The oil pump, a Leistritz screw pump, has an internal by-pass valve that should have been factory set to 7 bar.
the adjusting screw is external so you can adjust it with pressure on the system, unlike some others where you have to take the pressure off to access an obscure hex bolt behind a plug.

checked the travel with my wrench and found that it was bottomed out, all the way closed.

So now I had four things to check, hansen by-pass valve, oil pump by-pass, check valve, and oil pump suction mesh filter.

all these components could be easily shut off without degassing the entire compressor unit, so I figured I'd start there.

The Hansen valve was a quick check as I could take the top of and check that the piston moves up and down freely.
The piston has a microscopic U-sleeve and since I didn't have any spare parts I didn't take it out. it's a real flimsy design and I don't like it. I have logged a request with our design team that we request that the package builder use a ICS with a CVPP or whatever they are called now )

So scratch that and reassemble it.


Was interested in seeing what the oil pump and internal relief looked like, so I started taking the front cover off, heart in my throat as it had a thin flat gasket and I didn't have any replacement, and we all know what oil and heat does to those 1mm paper gaskets.

Luckily I got it off without breaking the gasket, didn't see any issues with the internal relief so I reassembled that.

On to the mesh filter in the pump suction, that was clean as a whistle.


Final inspection was the check valve
It's an on demand oil pump, so once you establish HP/LP difference the pump stops and the pressure difference is supplying the oil, so there is a check valve that prevents the pump from short circuiting when it's running

Also no issues.

So now I had to set the pressures of the internal pressure relief and the Hansen valve.

Here's the pipe diagram of the oil system to give you an idea:


So after pulling a vacuum on the part I had opened, I opened the oil supply valve from the oil separator (pos. 0170)

turned the adjustment screw on the Hansen as far as I dared clockwise to increase the opening pressure.

The adjustment on the oil pump is clockwise = lower pressure and counter clockwise = pressure up, so I let it all the way out clockwise, then pre-set it to 5 turns counter clockwise to make sure I wouldn't start at zero.

My laptop was connected to the PLC so I had it on an oil drum next to me so I could start the oil pump and watch the OPF pressure above the HP.

Started the oil pump and started cranking the adjustment screw until I had 7 bar, stopped the pump, then I unwound the adjustment screw and counted the turns for future reference before I set it back.

Then did the same thing with the Hansen valve, let it all the way down, started the oil pump and tightened the adjusting screw until I had 3 bar difference, then unwound it and counted the turns for future reference before setting it back.

Opened the valve before the oil filter (pos. 0360) and started the compressor again.

I had to add another 3 turns to the Hansen valve once the compressor started to maintain the OP/LP differential.


My observations as I ran the system this time was that there the OP sensor was slightly less erratic, but it still had random jumps from 6 to 15 bar, while the HP and OPF sensor would be dead stable.

The OP sensor was mounted on the side of the compressor:



I still haven't opened one of these compressors, and Hall hasn't sent us the drawings I have requested, so this is just an educated guess

According to Hall, if the compressor starts at low speed, it should start with 40% slide valve load...

My thought is that at low speed, with low HP/LP pressure difference, it is probably being overfed with oil and there is something in the compressor design causing an intermittent leak between the oil injection and discharge and suction.
Oil pressure may be low, but amount may be too high and cause the pressure to fluctuate.

So I installed a new pressure sensor here, directly after the filter:


I also did a 200 hour "filter service" on the plant and checked and cleaned all the mesh filters before the LRI AKVA and chiller AKVA valves.

The documentation says that there is a start up "filter bag" in the compressor suction strainer, and they had two new suction strainers on board, so I figured I might as well put the correct mesh filter in.

I'm used to danfoss filters, the covers there you can see that they are 15-20mm thick and you know they don't have any excess material, so a DN250 cover can easily be handled by one person.

This filter I believe was a GEA, so there I were, one foot on the frame, the other on an oil drum for balance, holding the cover with my left hand as I were wiggling it out against a slight vacuum with a screwdriver using my right hand.

And all of a sudden the cover came loose and I found out that GEA over engineers even filter covers!
I mean, the visible part of the cover was 2 cm thick, but there were another 3 cm inside the housing, and I were holding it up with my left hand, so when it came out I managed to grab it with both hands to break the fall so it didn't hit the oil pipe and cap solenoids, and I think i screamed like a girl, farted and burped at the same time as the oil drum I had one leg on shot out from under me when I fell forward under the weight of the thing...

In hindsight, I should have suspected that it might be heavy since it had two threaded M12 holes at 3 & 9 for pushing it out of it's seat, but most likely they were for attaching eye bolts to lift it back in place.

The mesh filter had to be sleeved onto the filter cover and then it fit a groove in the back of the filter house. there was no way to mount the filter inside the housing and then put on the cover.

we had to thread two M12x200 bolts in the threaded holes and it took two people to lift that darn cover back into place.

------------

Ok, that was a bit of a digression, but damn that is the heaviest filter cover I have ever encountered, and that night when I went to bed my left bicep felt like it had been torn from whatever it had been attached to and was just throbbing all night.
Those few seconds when I held that cover from slamming down onto the oil pipe and solenoids must have been like 2 years of bicep curls condensed into .5 of a second.

The kicker is that there was no filter bag installed...

Also I don't really see the point in having a filter bag in the suction on a compact RSW system where the suction line is 2 meters long
------------

Anyways, after vacuuming the compressor unit, I fired back up and OP was pretty stable after I had moved it... instead of oscillating 5 bar +/- it was oscillating maybe +/- 0,9 bar, so better but not good.

I didn't want to believe it, but it seems the oil filter is actually acting as a dampening device between the OP and OPF sensor.

I had a pressure gauge connected to both OP connections, and as you know the glycerine in the gauge acts as a dampener, I could still see the pressure on the gauge oscillate slightly, as in the needle wasn't stable, but it would move only around 0.3 bar



So in conclusion, adjusting the internal overflow valve on the pump, and adjusting the external pressure regulating valve, plus moving the sensor worked slightly...

as a final touch, we adjusted the 1 second filter on the sensor reading to 2 seconds and it was perfect.


To recap, here is a 3X speed video of how it was originally, and I have marked out the pressures you should watch, asnd you can clearly see how the OP is wildly going up and down while the oil pump is running.


This video shows the compressor running once it has established HP/LP pressure differential and the oil pump has stopped:
https://www.youtube.com/shorts/Y5ZGAOYtfs8

dead stable, as it should be

--------------------------------------------------------------

I think it's a band aid on a broken leg... and it's probably going to come back and bite someone in the butt...

[Tycho]

Oh and the Oil lines are so small and so short that there is a detrimental vibration.
I'm giving them 2-3 years before a weld or pipe cracks

https://www.youtube.com/shorts/Q9L_G-KJraM

[RANGER1]

Thanks for update Tycho,
Little bit different set up with oil pump on your system being a lot bigger.
Usually differential across machine happens reasonably fast, but maybe not in this case.
Oil filter differential looks high, not sure if you changed that out.
Strange how Hansen valve started to work, unless to much was going through it before pump adjustment.
Nice trip in the sunshine for you��

[seanf]

What filter setting did the OPF sensor have?

Shaky oil pipes on Hall systems dosnt seem too unusual.

[Tycho]

Thanks for update Tycho,
Little bit different set up with oil pump on your system being a lot bigger.
Usually differential across machine happens reasonably fast, but maybe not in this case.
Oil filter differential looks high, not sure if you changed that out.
Strange how Hansen valve started to work, unless to much was going through it before pump adjustment.
Nice trip in the sunshine for you��

It's an RSW system, and no ICS/pm between discharge and condenser, so it starts with 15C water in the tanks and on the condenser.

The diff pressure wasn't there until max slide and around 3000 rpm I believe.

The oil filter is fine once the oil pump shuts off and has a 0.1bar diff, so I left it in.
the reason you are seeing the oil filter diff is because it's calculated from the erratic sensor

Hansen valve was probably full open trying to get rid of the excess oil since the internal valve was fully closed, or so I believe

[Tycho]

What filter setting did the OPF sensor have?

Shaky oil pipes on Hall systems dosnt seem too unusual.

We run with a 1 sec filter time on all our systems, it keeps the decimal values nice and stable.

They all had 1 sec filter time, so if I understood our PLC guru correctly the value shown on screen is the average value in a 1 sec timespan.


I was itching to throttle the discharge valve to establish HP/LP diff from the beginning and see how it ran on low load (2400 rpm/40% slide) and if I could get it to start and run without the on demand pump needing to kick in, because once HP/LP diff is established and the pump stops, everything is dead stable.

I have plenty of excuses, but mostly it was because I was to scared to fire it up with the discharge almost closed

I have been thinking tho that instead of using a ICS with a CVP at a fixed discharge, it should be achievable with an ICS and ICAD or similar if they are fast enough during the initial start up to keep it from tripping on high discharge.

the cost of an ICAD and ICM should be approx the same as the cost of the oil pump and all the valves and filters needed to have it there.

There was also an issue when it was nearing setpoint on the water and was decreasing the speed it was going so fast it caused the oil to foam up and the oil level float dropped and tripped it, but that was an easy fix by just tuning the decrease timer.

[seanf]

Would having control of the condenser water flow give a quick enough build up of pressure?

[RANGER1]

A Danfoss KDC & ORV are commonly used in these situations, but lots of ways of doing things.
Oil pump is belts & braces.
I think Hansen & Parker used for years, as Danfoss PM valve did not have “V” port for better control.
ICS has changed that problem.

[Tycho]

Would having control of the condenser water flow give a quick enough build up of pressure?

condenser pump is VFD controlled from 20-60hz, even at low speed pressure diff doesn't build fast enough

[RANGER1]

Thanks Tycho for rep point

[Reggieros]

Would having control of the condenser water flow give a quick enough build up of pressure?

Controlling condenser water flow could potentially lead to a quick pressure build-up. Consider system dynamics and safety measures for optimal results.Magic 8 Ball

[Tycho]

Controlling condenser water flow could potentially lead to a quick pressure build-up. Consider system dynamics and safety measures for optimal results.Magic 8 Ball

Reggieros, Welcome to the forum

it's a good thought, but as I mentioned a bit further up, we are running the condenser pump at 20Hz during start up and it's barely lifting the water two decks up to the condenser, and if we run it any slower it will drop the water and start cavitating causing excessive wear on the pump.