Centrifugal Chiller Compressor Maintenance

Grey centrifugal chiller compressor being maintained

Centrifugal Chiller Compressor Maintenance

Centrifugal chiller compressor maintenance keeps your critical plant up and running and your customers happy. The work can be scheduled to be carried out during factory shutdown, so as not to disrupt your production. We can also carry out this work to your compressors while the factory is in production. This is achieved by isolating the compressor that needs to be worked on when it is in an off cycle. The compressors on remaining machines can carry on running.

Tasks during Centrifugal Chiller Compressor Maintenance

Here are some of the tasks that we carry out…

Oil Changes

The oil becomes dirty over time by picking up contaminants that have formed in the system. Two of these contaminants are…

Acid

Compressor discharge is the hottest part of the refrigerant cycle. Acid can be formed from the refrigerant in this part of the system.

Refrigerant Types

A popular refrigerant for centrifs is R134a. Because it consists only of one kind of refrigerant, it does not fractionalise into different component refrigerants. This would be no good for a flooded system because one or more of the refrigerants would end up in the bottom of the evaporator and condenser. The remaining refrigerant would circulate and the whole plant would not function as it should. Refrigerants popular for other kinds of system are zeotropic HFC refrigerants. This means that the different component refrigerants have different boiling points- R407c is a good example.

Metal

White metal from the compressor and copper from the heat exchangers end up in the oil. They will eventually be caught by the system oil filters…

Oil Filter Change

After completing the above, now is a good time to change the filter as the compressor is valved off and has been broken into. It is also when an oil sample is taken depending on the schedule…

Oil Samples during Centrifugal Chiller Compressor Maintenance

Our oil samples are transported using our specialist kits which include the bottles and labels. This saves mix ups in our laboratory during the analysis.

Leak Rectification

The drawback of carrying out the above are leaks because the pressure has been pumped out of the compressor into another part of the system. The ‘o’ rings and shaft seal can now leak, this kind of failure can be rectified whilst still on site by the knowledge of our engineers.

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Oil Pre Lubrication

When the compressor starts, the oil pressure is built up first using an oil pump. This is so the internal components such as the high and low speed shaft are properly oiled before they start to rotate. They can run at 10,000 RPM and are very expensive to replace. Therefore, we check the oil pressure gauges and the system controls to ensure optimum ‘pre lubing’ of your compressors.

Volumetric Efficiency

The ratio between the volume actually compressed and the theoretical volume derived from compressor design calculations. This kind of compressor has a lower volumetric efficiency than positive displacement compressors. It is because the refrigerant is compressed off the tip of the rotating impellor or impellors. The refrigerant moves outwards in a circular path due to centrifugal force. A centrif more than makes up for this lower volumetric efficiency by the high mass and volume of the refrigerant that it circulates around the system.

Design 

The refrigerant is sucked from the evaporator into the centre of the impellor which is a disc of radial blades positioned to direct the refrigerant outwards. Due to the low differential of pressure, multiple stages of impellors are often arranged in series with the discharge being directed onto the suction of the next impellor. This is simple in design with less moving parts than some other compressor types. Modern centrifs can have magnetic, levitating bearings and so remove the need for oil in the system altogether. The faster the speed, the better the efficiency- so high speed rotation of the impellor is achieved at full load. The compressed refrigerant is discharged into the condenser.

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Electric Drive Centrifugal Chiller Compressor Maintenance

Most modern centrifs are driven by variable speed drives. This is for efficiency as the load can be exactly matched. Another reason for this is to soft start the compressor. 415v and 3.3kv are popular volt inputs, although other voltages can be made available by the onsite transformer.

Open

An open drive electric motor is the most popular design. It has the drawback, however, of needing a shaft seal which needs to be replaced at periodic intervals. This shaft seal is also prone to leaking refrigerant and oil.

Semi Hermetic

The photo is of a semi hermetic design of this compressor type. The motor is contained inside the suction housing and so has the benefit of being cooled by the refrigerant. No shaft seal is needed and therefore it has none of the associated maintenance drawbacks.

Steam Drive Centrifugal Chiller Compressor Maintenance

On oil rigs there can be an abundant supply of steam that can be used to drive the compressor. It is often used on multi stage compressors which are used for the liquefaction of natural gas. The steam goes through a turbine which is connected to a shaft- this drives the impellors. The steam flow and pressure can be tested and adjusted during the visit.

Woops Something Went Wrong

When you suffer a centrifugal compressor failure- don’t worry. You are in safe hands with the team here at Maximus Chillers. We have a team who can get the compressor out and lift it to the workshop on site, or transport it to our Head Office. We have another team who are experts in the remanufacturing of this kind of compressor. A fast supply chain is in place for delivery of the internal moving parts, gaskets and bearings. We are so confident that you will be happy with us- we offer a 12 month warranty on all of our compressor rebuilds.

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Chiller compressor failure of blue Grasso in enclosure

Chiller Compressors

System Testing for Chiller Compressors

Chiller compressors fail often as a result of ineffective servicing and system testing. At Maximus Chillers, we carry out extensive tests during our visits to ensure that small problems are resolved before they become big problems. If we notice a reading starting to become abnormal, we can carry out the diagnosis and then remedy the problem. Some of the compressor readings we monitor are:

Temperature of Chiller Compressors

The suction, discharge, motor windings and bearing temperatures are recorded for comparison to previous visits. These are often available in the PLC for the chiller, or our engineer can take the readings with his test equipment. Problems with the oil cooler can be the cause of higher compressor temperatures, the system running outside of its nominal operating conditions is another reason. Magnetic drive systems have an advantage as they do not use oil.

Accelerometer

Portable vibration sensors are carried in of each of our company vehicles. This is an accelerometer to measure vibration. Along with other system readings, we keep an on going record of the vibration levels around the compressor. When internal components are coming out of alignment due to wear, this causes an out of balance condition in the compressor. This, in turn, causes a knock on effect- causing other components to go out of balance. Catching this condition early will prevent a compressor smash up resulting in the replacement of expensive internal components.

Oil Analysis for Chiller Compressors

Another way of preventing big problems from occurring is periodic compressor oil testing. Samples are taken, usually on alternate visits, which are sent off to a laboratory for analysis. The acid level is tested to provide pre warning of a potential compressor motor windings burn out. This is because acid in the compressor oil rots through the electrical insulation on the motor windings. The presence and quantity of white metal and yellow metal is analysed too. This is a window through to a component starting to wear inside the compressor.

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Screw

The compressor in the photo is a screw compressor. It operates with ammonia refrigerant. This refrigerant is usually used for low temperature applications, mainly associated with food production. This compressor, however, has a 1°C refrigerant saturation and is used to cool computer rooms. Common causes of compressor failure on this kind of compressor are:

Leaking Castings on Chiller Compressors

The various compressor components are sealed together using ‘o’ rings or paper gaskets. ‘O’ rings are especially prone to leaks due to work hardening and flattening of the sealing face. The system can be pumped down and the compressor valved off. Then, our lift and shift team can remove the compressor to our remanufacturing facility for strip down.

Leaking Shaft Seal

The mating surface of a shaft seal has a mirror smooth finish. This is to reduce friction and aid with a better seal. Over time, this starts to wear, causing an ineffective seal with a leak of refrigerant and oil. A service visit can be arranged to change the shaft seal on site. The shaft couplings can be split, the shaft seal can then be removed and replaced. A quick job, then the machine is up and running again.

Slide Valve Potentiometer

This is an electronic device with a slide attached to the moving compressor slide valve. The device has a start and an end position programmed into it during commissioning. The potentiometer converts the slide valve position, usually into a 4-20mA signal which is fed back to the chiller PLC. They are prone to reading out, or the reading being jammed in one position. This results in a trip out from the controls, as the controller is not able to determine the true position of the compressor slide valve. We have an off the shelf stock of slide valve potentiometers for the various compressor range. A service visit can be arranged to replace the part after diagnosis has been carried out. The controls operate the loading and unloading solenoid valves to change the position of the slide valve.

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Centrifugal

Centrifugal compressors are a very reliable kind of compressor but when they go wrong, they can go wrong in a big way. Compressor overhaul is expensive, this can be carried out onsite, or a better option is a lift and shift to our remanufacturing facility. Proximity sensors are usually fitted to monitor the distance between the impeller and the casting. This is an added protection along with the other sensors and transducers around the compressor.

MCS

We are on account with Micro Control Systems- an American company who specialise in building panels to order for specific chiller compressors. We easily fit this control system to any compressor to control the loading of the vanes in accordance to the available load from the process. The control panel has previously been fitted to other machines of the same model number, so any teething issues have already been ironed out. Maximus Chillers can achieve seamless operation of your plant.

Oil System for Chiller Compressors 

Newer centrifugal compressors are oil free so as to eliminate any of the service issues relating to oil. There are a substantial amount of compressors, however, that use oil to lubricate the bearings. This kind of compressor, if properly serviced, can last for 50 years. The oil system picks up impurities which are caught by various filters. These filters can be changed or cleaned according to the prescribed service schedule. Our engineers make sure that spares are ordered and kept onsite prior to a visit.

Cost Effective

Our visits and ongoing upkeep of your plant saves money. Money spent as a preventative measure saves so much more money in the long run. With competitive prices on specialist internal centrifugal compressor parts- Maximus Chillers completes the picture. When compressor failure occurs, you are in safe hands with years of industry experience invested in each of our engineers.

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Scroll

These are some issues affecting a scroll compressor:

High Discharge Pressure

With high discharge pressure, there is a corresponding increase in discharge temperature. This means that the compressor is operating beyond its recommended values. The cause of this is often a poorly maintained condenser. Especially on industrial chillers, there can have been gaps in the schedule where the condenser was not correctly serviced. This condition is often rectified easily by an onsite engineer by giving it a brush down. Where the fins are bent over- we carry a specialist tool to straighten them back out- how they came out of the factory. We also use different formulas of chemicals to rinse the various kinds of dirt from deep within the fins.

High Suction Pressure on Chiller Compressors 

Some chillers are used where very high water temperature can come back from the process if the chiller were to be off line for a short period. Usually, this happens in factories where certain industrial processes are being carried out. When the onsite engineers start the plant back up, the chiller experiences a high heat load to deal with.

MOP Expansion Valves

Maximum operating pressure expansion valves limit the pressure in the evaporator to a given level, regardless of the available heat load from the process. They do this by having a limited amount of liquid refrigerant in the bulb. When this runs out, the power element cannot push the orifice open any further- thus limiting the suction pressure. This is important to prevent scroll compressor failure as it prevents putting added strain on the compressor motor windings due to high suction pressure.

Oil and Refrigerant Shortage

Where there is a shortage in refrigerant, there follows a low oil level condition. The refrigerant mass flow rate carries the oil around the system and back to the compressor. This is greatly impaired when the chiller is short of gas. The oil cools the compressor and lubricates the shaft bearings. These bearings and other internal components wear down and seize causing failure. Maximus Chillers can put together a package to minimise chiller compressor failure.

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PLC and relay board in a panel during chiller service company visit

Chiller Service Company

Electrical Testing

A chiller service company can carry out electrical testing and diagnosis even when a wiring diagram is not available- our engineers can trace the wiring around a chiller.

News Article No.3

Doing this often aids with the diagnosis even when there is a wiring diagram, as having your eyes on a component often makes more sense than a symbol. In any case, our engineers carry out system testing with Fluke multimetes and ammeters.

F-gas Leak Testing by Chiller Service Company

We also carry a range of thermocouples and probes to be used in conjunction with our calibrated digital thermometers. We use these along with comparators to carry out leak testing. After fitting the probes, we first have a visual look around for a sign of a gas leak. All parts of the pipework and system components are inspected. Then, we carry out a full refrigerant diagnosis to determine that the refrigerant system is operating with a full charge. Reports for each chiller are completed and filed in the onsite F-gas leak register. A history can be built up to assess the serviceability of the plant and the frequency of any leaks.

Chiller Service Company Monitoring

Where intermittent faults are concerned, on site monitoring is required. If the job is not progressed on each visit, there is little point in a call out. We carry out tests during monitoring and ensure that the wiring is tight. Hopefully, waiting for the fault to occur whilst next to the machine. Alongside this, we rely on feedback from the end user, as regards, the symptoms and the circumstances of the chiller when the fault occurred. From this we extrapolate the diagnosis and decide the next step to take. This may be to attempt to move the fault to another machine or, at least eliminate one thing each visit.

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Chiller Service Company Evaporators

Shell and Tube

These have a rolled steel shell, welded down the seam with and end plate on either end. The water system pipes can be bolted to the sides or the end. The endplate can be removed for access to the waterside of the tubes. A strainer is fitted to the inlet to catch any foreign objects that may have been carried around the water system. Inlet and outlet gauges are fitted for the monitoring of the water system readings during a visit. 

Flooded

On larger chillers, the screw or centrifugal compressor is mounted directly on top of the flooded evaporator. The refrigerant is in its liquid phase on the outside of the tubes. These are arranged in a rack extending through the length of the shell. The warmer process water running through the tubes causes the refrigerant to boil off. A sight glass is usually available to check the state of the refrigerant evaporating on the copper tubes. The suction from the top of the evaporator goes round a baffle so as to prevent the slug back of liquid refrigerant into the compressor. The refrigerant flow into the evaporator is controlled by the expansion valve…

Expansion Valves

This takes the form of a fixed size orifice on the liquid line in between the shell and tube condenser and the flooded evaporator. The size of the orifice previously being calculated to match the mass flow rate of the refrigerant dictated by the compressor. Some newer systems have a variable orifice for the more efficient running of the plant. This is controlled electronically along with the loading of the compressor, relative to the available load.

Multiple System N+1

Smaller DX evaporators are usually multi system. This gives an N+1 redundancy of the plant. Indeed, when one side of a 2 system evaporator is having service work carried out, the other side continues to operate normally. Thinking ahead and allowing for additional capacity is essential when the application is critical, such as, a data centre or a hospital. When a redundant system comes online due to a failure- getting the failed system back up and running is a matter of urgency. For this we offer same day delivery of parts and a fully stocked mobile workshop.

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Chiller Service Company Condensers

Various configurations are employed to ensure good air flow through the condenser fins. The most popular being a ‘v’ condenser as the surface area is increased with this design. Powerful fans are used to reject the air and heat upwards and away from the chiller. Where system location causes the recirculation of air, duct work can be fitted to direct the air away from the chiller. The pressure is monitored using a HP gauge.

Pressure Transducers

Johnson Controls

A popular kind of pressure transducer that is used on condensers is Johnson Controls. These can be bolted onto the refrigerant discharge pipe to sense the system pressure. They have a 5vdc input that comes into the transducer on a red wire, a black wire is the ground and a white wire is the signal back to the fan speed controller. The transducer has a minimum to maximum range, so a chart can be used to determine if the signal is reading back correctly. On chillers where the transducer is wired directly in the controller- calibration can be carried out to offset the readings.

Keller

Another kind of pressure transducer is the 4-20mA type. It sends a mA signal back to the controller or the fan speed controller. 4mA is the minimum position, so this relates to the minimum of the transducer pressure range.

R134a Refrigerant

R134a refrigerant operates at a lower pressure in a condenser than the other commonly used HFC refrigerants. If you were looking for a chilled water set point of 6°C in the UK ambient for example, the R134a refrigerant saturation on the high side of the system would be around 36°C Latent heat from the water system and heat added into the refrigerant from the compressor are rejected from the condenser. As the refrigerant passes down the condenser tubes, cool air blowing across the outside of the tubes, cools the refrigerant vapour down through the latent heat phase and into a subcooled liquid.

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Chiller Service Company Compressors

Centrifugal Compressors

This kind of compressor has a lower volumetric efficiency compared with the positive displacement compressors below. This is because the refrigerant is compressed using centrifugal force off the tip of the impeller, instead of being mechanically compressed. The advantage of this kind of compressor is a high mass flow rate of refrigerant. These compressors are used in factories where a large amount of chilled water is required to cool the process. They are also used in countries where district cooling is used. The chillers are arranged in rows in a chiller hall and are piped into the district cooling loop.

Screw Compressors

Oil used to lubricate the bearings is also used to create a seal between the rotors. Computer aided design (CAD) software and computer numerical control (CNC) grinding machines are used in the construction of screw rotors. The shape of the rotors is designed to compress the refrigerant along the screw. The length of the screw that is available to compress the refrigerant can be adjusted with a slide valve. Any stage of loading between 0- 100% can be achieved. This is regulated with a slide valve potentiometer. Screw compressors are very reliable and have a long service life. They also have a low vibration reading which ensures a lower instance of refrigerant leaks around the compressor.

Scroll Compressors

A service free compressor. Service free assuming that the rest of the system is functioning correctly. This kind of compressor relies on oil migration around the system. The oil is entrained along the inside of the pipework, around the system and back to the compressor. An oil level sight glass is fitted into the body of the compressor at the required level. Refrigerant shortage can cause the oil to stay in the bottom of the evaporator, causing a low oil level condition in the compressor. We can be scheduled to attend site to drain the oil, then pump new oil into the compressor.

Compressor Failure

When any of the above compressors fail, you are in safe hands with Maximus Chillers. We have the capability to lift and shift the compressor to our remanufacturing facility for a full overhaul. The reason for the failure is diagnosed to ensure the new compressor does not fail for the same reason. Improving the reliability of your plant and extending its life is what we are all about- if we can reduce your service costs- that makes us happy! All temperatures and pressures are recorded to ensure the replacement compressor goes into seamless operation.

Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere- The MAXIMUS ADVANTAGE™

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Yellow oil drums, ammonia refrigerant cylinders and flammable flushing agent of chiller supplier

Chiller Parts Supplier

Chiller Parts Supplier of Compressors

Centrifugal

As a chiller parts supplier, all kinds of centrifugal compressors are remanufactured in our workshop. With an overhead gantry crane and specialist equipment to hand- Maximus Chillers completes the picture. We have a lift and shift team who are skilled at getting the compressor out of the most awkward locations. A variety of lifting equipment is used, including 3 phase electric hoists and trollies. Our team do this kind of work all the time, so they are accustomed to overcoming all the difficulties and obstacles.

Screw

Screw compressors are remanufactured on the bench. With compressed air and bearing tools- our skilled technicians are seasoned in high tolerance measurements. The bearing clearance and shaft run out are accurately measured and adjusted. This means that the useful life of the compressor is extended, often to beyond the lifespan of the chiller.

Scroll

We have a range of off the shelf Copeland compressors for a fast lead time on process chiller repairs. These can be sent to site on the day using our fast door to door supply chain. We have all the sizes of compressor available. The pipework and mountings can be adapted too. This means that if your compressor is a different make with a longer lead time- our compressor will be fitted and adapted to your machine- fast!

Chiller Parts Supplier of Condensers

Air Cooled

When the condenser on an air cooled chiller is in poor condition- our site survey team will attend to measure up for a new bespoke condenser. This is done free of charge and ensures that the new condenser will fit easily into the old chiller. The exact subcooling requirement of the old condenser is taken into account which is duplicated on to the new condenser. This means a like for like swap can take place even when the old condenser is obsolete.

Shell and Tube

This type of condenser is used on water cooled chillers. It is protected from contaminants by a strainer on the water system. We have these condensers built to order by our bespoke manufacturer. They are shipped to site on an overnight delivery, so we can get straight down to work in the morning. We therefore minimise downtime in the swap out of this part.

Chiller Parts Supplier of Evaporators

Shell and tube are the most popular type of evaporator for large chillers. The low temperature refrigerant is on the outside of the tubes in liquid form. The water is pumped through the tubes, releasing heat from the process and into the refrigerant. This is latent heat as the liquid refrigerant boils off into a vapour. Where the heat exchange does not greatly improve after cleaning, we recommend replacing this part.

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Vibration Eliminators

We have all of the sizes of anacondas on the shelf in our stores. This saves on the delivery time to site when your process is off due to the chiller. Maximus Chillers will get you up and running- fast! We can also fit flexible vibration hoses which achieve the same result as anacondas. Whereas two anacondas are fitted vertically and horizontally, only one, long vibration hose is needed.

Chiller Parts Supplier of Flushing Agent

When things go wrong, we stock a solvent based flushing agent which is blown through the system using nitrogen. The waste product is caught on the far end in drums that come with the kit. This is then returned to the suppliers for recycling.

Refrigerant Economizers

These are another term for a subcooler. If the refrigerant is further subcooled after the condenser- the system will run more efficiently. This part usually takes the form of a plate heat exchanger with an expansion valve providing the refrigeration effect needed to further subcool the remaining liquid.

Chiller Parts Supplier of Pressure Transducers

We can make temporary repairs to faulty pressure transducers using our test equipment. This will keep your plant running while the part arrives on site. Then we can get your chiller up and running with the correct readings in the controls. This will assist your onsite maintenance engineers in giving us useful readings when we are in communications over the phone.

Chiller Parts Supplier of Ammonia and HFC Refrigerant

A full selection of refrigerants are available including: anhydrous ammonia, R407c, R134a and R410a. These refrigerants come in small 12kg, midi 26kg, large 56kg and bomb 800kg sizes. Our vehicles are equipped with tail lifts and lifting gear to facilitate delivery. We can therefore arrange the delivery and collection of refrigerant at your site, free of charge, anywhere in the UK. For our overseas customers, we arrange the transportation from the local suppliers.

Chiller Parts Supplier of Oil

Low, medium and high viscosity oils in 5ltr cans and 20ltr drums are ready for shipping from our storage area. It is critical to select the correct grade of compressor oil as bearing wear and reduced service life will result. We take regular samples of this oil to see if things are starting to go wrong in the compressor. We can then nip these problems in the bud, giving you dramatic savings.

Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere- The MAXIMUS ADVANTAGE™

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Two dark green centrifugal chillers undergoing maintenance in plant room

Centrifugal Chiller Maintenance

At the beginning of the year we completed centrifugal chiller maintenance for one of our customers in America. A last overseas trip for the moment given the current world lockdown. The machines in the photo chill water that is pumped around a university campus.

Centrifugal Chiller Maintenance of Redundant System

The plant has a water cooling shell and tube evaporator and a water cooled shell and tube condenser. It has been designed according to the N+1 principle: N being the amount of cooling required and 1 being that same amount of cooling again. Each chiller has enough capacity to satisfy demand. Given the large size of the campus, this principle was critical to keeping the University functioning should system failure occur. The chiller on the right was the lead chiller on arrival. After taking detailed readings during the maintenance, our engineer switched that chiller over into being the lag chiller and took readings from the chiller on the left. He rotates the lead/ lag of the chillers on each visit to balance the run hours of the compressors.

Volumetric Efficiency

Centrifugal chillers have a lower volumetric efficiency compared with positive displacement compressors such as screws and recips. This is because the impeller does not mechanically compress the refrigerant like a piston in a reciprocating compressor. This kind of compressor relies on centrifugal force to spin the refrigerant off the tip of the impeller and onto the next stage. The refrigerant is then discharged from the compressor.

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Mass Flow Rate

The above is more than compensated for with a high mass flow rate. That is to say: a high volume of refrigerant circulates around the system at its operating density. A large capacity machine is cost effective when considering energy efficiency and centrifugal chiller maintenance costs.

Gantry Crane for Centrifugal Chiller Maintenance

The gantry crane in the picture is available to aid with the lift and shift of the compressor, should compressor failure occur. Maximus Chillers are specialists in the overhaul of centrifugal compressors. We can arrange the lift out, transportation, strip down and reassembly of your compressors. All of our strip downs come with a 12 month warranty to give you peace of mind and confidence in our ability.

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Ammonia refrigerant cylinder being winched up a cat ladder using a block and tackle

Industrial Refrigeration Ammonia

The industrial refrigeration ammonia visit was at a site in Aberystwyth. We look after 2 ammonia chillers for a blue chip customer. They are 10 year old chillers that have been designed to need ongoing attention. Quite easy job as the faults they go into are reoccurring round in a circle. They have previously had the same problems.

Ammonia Shaft Seal for Industrial Refrigeration

The shaft seal had started to leak ammonia. It was replaced by removing the shaft seal cover, splitting the coupling and sliding the shaft seal over the shaft. After removing the non condensables, we reintroduced the ammonia back into the compressor- now the 'o' rings leaked.

Leaking Industrial Refrigeration Ammonia 'O' Rings

Leaks on ‘o’ rings occur because they become flattened and plastic like. This is caused by heat around the high side of the screw compressor. When there is pressure in the system- the oil if forced against the gap- making a seal. After the ammonia refrigerant had been handled- the oil ran away- causing a leak when the ammonia was reintroduced.

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Lift and Shift Visit

The pipework and ancillaries had been removed from the compressor prior to the visit. Our lift and shift guys arrived and set up their lifting equipment. They raised the compressor and manoeuvred it on across the roof. They then manoeuvred it up then down some steps. They used lifting equipment to get the compressor, end on- down a cat ladder.

Compressor Strip Down

It is always better to strip down this kind of compressor in a workshop- on a bench with compressed air and all the tools nearby. We unbolted the castings and slid the screw out. The various castings being laid out in a line. We replaced the ‘o’ rings for new the rebuilt the compressor.

Industrial refrigeration ammonia being charged by an engineer wearing breathing apparatus and gloves
Ammonia refrigerant being sucked into the low side of a flooded evaporator

Ammonia Refrigerant Charge

Part of the ammonia refrigerant had been handled during the visit. This left the compressor pipework, compressor and the oil separator open to atmosphere. The non condensables were evacuated. In the photo we are lifting the cylinder up a cat ladder into the plant room. From there it needed to be man handled up some steps, down some steps and out onto the roof. We charged the ammonia plant with liquid ammonia until the superheat and subcooling values were within industry known limits. The sight glass levels and condition were monitored too.

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