Questions about your quotes and orders.

How do i start to make orders ?

First you must register and tell us who you are.

Once we have this information we moderate the registration and contact you with our reply and account details.

You can then log in and make orders . 

Where do we ship parts ?

We ship to anywhere in the World* and where possible we introduce our local Ztechnique distributor to support you.

*Excludes Embargo country's 

Where are Ztechnique Distributors located

We currently (2020) have Ztechnique distributors in 17 country's.

In the USA alone we have 3 master distributors and several other sub distributors covering huge areas of the USA and Canada.

Areas Covered 

Costa Rica

And more....

If your interested in becoming a Ztechnique distributor you can contact us here now 


What shipping methods do you use

We normally quote 'Ex Works' for new inquiry's

Where requested we can enable a carrier for customers at additional cost to the quoted parts.

We will provide track and trace for all orders shipped by ourselves 

For more information on shipping options contact us 

Warranty Claims

In the unfortunate event that you have to make a warranty claim we are able to deal with your request very quickly.

Contact our company by clicking here and sending us details of your order number.

Return of goods is your responsibility, however if the goods are found to be damaged and under warranty we will endeavour to reimburse the transport cost for you*

* at the discretion of the stores manager

Support Documents

PDF Support Manuals

Where legally possible we will send you support documentation for your compressor (PDF Parts and Instruction manuals) by email after you become a customer of Ztechnique 

Warranty Support

We provide a comprehensive warranty package for our customers both on consumables and metal products.

Our new Ztechnique replacement elements for Atlas Copco Z and GHH equipment has a standard warranty of 12 Months for refurbished & 18 months for new Ztechnique elements .

Warranty on these items can be extended to 40,000 hours run providing a service contract is in place with our representative.  


How do we get oil free training ?

Ztechnique runs regular oil free training schools throughout each year on Atlas Copco Z and MD equipment. We have a dedicated training centre in St Helens Merseyside fully equipped with ZT ZR ZA ZE & MD equipment to train you to a very high standard 

This enables customers and distributors to gain the necessary skills to confidently install our parts and obtain warranty if required.

For information on 2020 training classes contact us here now 

Performance of our parts

How do your parts compare to OEM ?

We pay particular attention to ensuring that the compressed air parts we supply have been internally tested and meet our quality standards. 

OEM (Original Equipment Manufacture ) can be confusing because the spare parts that a compressor manufacturer sells could have been produced by a third party and re branded to appear to be manufactured by the compressor supplier.

In many cases (take oil as an example ) the compressor manufacturer does not refine the oil they sell, they merely re brand the oil from other suppliers to appear like it was produced by the compressor manufacturer.

Ztechnique are very open about our 're branding' of our suppliers spare parts and often seek the same parts to re brand (Siemens contactors for example) but at lower re sale cost than the OEM,s

Which oil free air ends do we produce ?

Whos air ends do you replicate ?

We currently produce NON OEM air ends for Atlas Copco and equipment using GHH air ends like Ingersoll Rand for example.

We can refurbish your own elements you free issue to Ztechnique or we can supply you with new Ztechnique elements for these compressors.

In 2020 we can offer you NEW and refurbished GHH air ends from the OEM and alternative suppliers 


Are refurbished as good as new Elements ?

No you will never get the exact same performance as a new oil free element from a refurbished air end.

The normal difference is between 5 to 10% less efficiency due to re use of the key components .

Where new rotors are installed on refurbished element's from Atlas Copco and GHH compressors the efficiency increases to between 3% to 5%

Whilst many customers prefer refurbished instead of the cost of new elements the small loss of efficiency is agreeable when compared to OEM new prices. for more information about our air ends click here 

Can we buy new Ztechnique elements from you ?

Yes we have a range of new Ztechnique elements for Atlas Copco and GHH fitted equipment.

The price is considerably less than New OEM prices and the efficiency is within 1/2%  efficiency claims the OEM makes for its products.

Each air end is supplied with a test certificate showing the test has been carried out at our Merseyside test facility for 2 hours duration

Are your elements oil free ?

Yes exactly as the manufacturer states the design of the Ztechnique elements mirrors the OEM design by not allowing any oil to enter the compression chamber. 

Any oil passing the internal seals is sent down 'vent holes' to atmosphere and cannot contaminate the customers product.

Our design of our air and oil  seals has been proven to be as efficient as the design allows for sealing efficiency and promotes long life when paired with our proven coating material 

Is your rotor coating as good as the OEM material ?

We have worked very closely over many years with our coating provider.

Our coating has proven to work better in harsh environment's that the OEM choice of coating.

Our coating has a higher temperature threshold than some OEM,s and it has nil silicone or Teflon present making it suitable for the tobacco and vehicle industry.

Our coating is not a 'sacrificial' coating as some OEM,s prefer. Our coating is hand applied to very strict quality procedures.


NON OEM MD Dryer Rotors

Is Ztechnique MD Rotor Material Hard wearing

We use a high quality silica rotor material sourced in Europe. 

The life expectancy of an MD dryer rotor is 40,000 to 50,000 hours in good running conditions.

Rotor life can be affected by poor maintenance scheduling , frequent load , unload patterns , poor dryer tuning and lower than recommended regen temperatures.

For more information and warranty explanation pertaining to MD dryer parts please contact us 


Replacement Coolers

Are your ZR ZH coolers comparable quality to the OEM

Our coolers for Atlas Copco ZA ZR ZH equipment are our own Ztechnique brand.

The selection of cooler materials is very important to the longevity of the coolers.

Our coolers are plug and play with the original cooler housings.

We also supply a range of cooler install kits for ZA ZR ZH replacement coolers.

Our standard warranty on our coolers is 12 months from date of installation.

Warranty claims may subject to water quality inspections and use only  on closed circuit cooling systems.

Do you supply coolers for Ingersoll Rand Centac models

Yes we supply a full alternative cooler range for Ingersoll Rand Centac turbo compressors.

The quality of our coolers is very high and sourced in Europe.

Warranty is 12 months from the date of install subject of course to water quality conditions on site. Warranty claims may be subject to water quality testing.

If you need specific details of our products you can email a representative by going to our contact page 

Brands we support

We support several brands of compressed air equipment

We support several brands of compressed air equipment that includes the following.

More Information can be found at each brand name link to a dedicated support page 


learn more about these brands by either searching our web site database or reading about the alternatives for spare parts and lubricants 

Need a quotation ? click here and contact us now 

Troubleshooting IR Centac units

Failing to start

1. Failure to clear shutdown or interlock devices.

Check : Correct shutdown or interlock condition that is indicated by the panel light

2. No Primary power to starter

Check : Check voltage to starter, check fuses

3. Loose or corroded connection or defective power cables 

Check: Check conditions n. Clean tighten and replace as necessary

Defective motor starter or starting circuit

Check: Troubleshoot starter per manufacturer instructions 

Ineffective pre lube pump

Improper adjustment. of prelude pump relief valve 

Check : Adjust relief valve for correct pressure 

Pump not Running 

Check : Troubleshoot pump starter. Check for proper voltage 

Defective Motor 

Check: Repair of replace motor 

No seal air (seal interlock is optional feature ) 

Check : Establish seal air 



High Oil Temperature

Low or no water flow to oil cooler 

Check: Establish correct water flow 

Higher water temperature than realised 

Check : Take necessary steps to lower the water supply temperature 

Improper temperature devise setting 

Check : Calibrate Instrument 

Dirty or plugged oil cooler on water side 

Check: Clean cooler tubes , provide water strainers as required 

Low Oil Pressure

Improper adjustment of system relief valves 

Check : Adjust system pressure relief valve for correct oil pressure in manual 

Leaking or pinched oil line 

Check: Repair or replace oil line 

Dirty oil filter 

Check: Replace with clean filter 

Defective main oil pump 

Check: Repair or replace main oil pump 


High Air Temperature

Low or no water flow to air cooler

Check: Establish correct water flow 

Higher water temperature than realised 

Check: Take steps to lower the water temperature 

Improper temperature device setting

Check: Calibrate device 

Dirty or plugged air cooler on water side 

Check: Clean water passages in cooler. Provide water strainers as required . Contact your service provider 


Low Seal Air Pressure

Low instrument air pressure 

Check: Check seal pressure. Check supply is clean and not wet or contaminated 

Improper adjustment of seal air pressure 

Check: Adjust regulator to obtain correct seal pressure (consult manual) 

Excessive bleed off valve adjustment (if supplied ) 

Check: Reduce seal air bleed off 

Worn seals

Check: Replace seals , consult your service provider 


Low Instrument or Valve Operating Pressure

No supply pressure , pinched or leaking air lines 

Check: Establish instrument air supply pressure. Repair or replace the air lines 

Improper adjustment of air regulator 

Check: Adjust regulator to obtain correct instrument air pressure 

High Vibration

Low oil temperature 

Check: Allow warm up period for oil

Worn coupling or spacer. 

Check: Lubricate. Replace coupling and /or spacer 

Rotor assembly unbalance due to foreign matter build up

Check: Contact service provider , cleaning and balance required 

Rotor assembly unbalance due to damaged components 

Check: Contact service provider. Repair re balance required 

Induced vibration from driver 

Check: Balance motor rotor 



Failed to load

Mode selector switch in UNLOAD position

Check: Turn selector switch to Modulate or Auto Dual operation mode 

Low set point on pressure controller 

Check: Adjust controller to desired set point 

Bypass valve not closed or inlet valve not open 

Check: Correct improper operation of the inlet or bypass valve 


Low System Air

Compressor not loaded 

Check: See ' Fail to load' above.

Dirty Inlet filter

Check: Change air filter elements 

Low Surge

Check: See 'Continual surging' below 

Greater demand than realised 

Check: Repair factory air leaks , turn off unnecessary demand


Continual Surge (pumping)

Discharge block valve closed 

Check: Open block valve 

Improper adjustment of throttle limit (LLR, CLL, TL)

Check: Adjust Throttle limit

High Interstage temperature 

Check: Establish correct water flow to air coolers , check for contamination 

Higher water temperature than realised 

Check: Reduce the cooling water temperature. Check inlet temp.

Worn or fouled aero parts 

Check: Contact your service provider 




Excessive Power Consumption

Lower ambient than realised 

Check: Reduce compressor load and contact your service provider 

Low primary voltage

Check:Consult power provider. Check power source 

Reduction in motor efficiency. Excessive load 

Check: Consult motor manufacturer. Reduce load 


High Drive Motor Amperage

Low primary voltage 

Check: Restore voltage to specification

High Load 

Check: Reduce load 


ZR ZT typical faults

How do I know if my High Pressure element is failing

On a ZR ZT Atlas Copco oil free compressor you can accurately pinpoint an HP element starting to fail

1. The Intercooler pressure will be rising well above its normal range of operation 

2. The Low pressure element exit air temperature will rise above its normal limits indicating the High Pressure element is in decline.

In this situation you should record your temperatures and pressures and call your local Ztechnique distributor with your readings. From these readings the distributor will advise accordingly on further tests and pricing to replace your element 

If you need to consult a Ztechnique expert click here now 

Typical Low Pressure element failure

On a ZR ZT Atlas Copco oil free compressor you can accurately pinpoint an LP element starting to fail

1. The Intercooler pressure will be falling (below 1.9 bar) its normal range of operation bar typical.

2. The high pressure element exit air temperature will rise above its normal limits indicating the Low Pressure element is in decline.

In this situation you should record your temperatures and pressures and call your local Ztechnique distributor with your readings. From these readings the distributor will advise accordingly on further tests and pricing to replace your element 

If you need to consult a Ztechnique expert click here now 

Identify an intercooler fault

If your interstage temperature is alarming on your compressor control panel, its likely to be either an external (air cooled) or Internal (water cooled) restriction. This is normally due to either by dust on the matrix of the cooler (ZT) or dirt blocking the intercooler tube assembly (ZR) reducing flow and cooling efficiency.

This will be identified with the HP inlet air temperature soaring above its normal range 40 to 50' (alarm at 60'c trip at 70'c ) 

In the case of a ZT compressor you can check the situation with a torch and the compressor stopped and view the cooler external condition. Clean the cooler with an air line and see of the cooler temperature reduces. If it doesn't reduce then the material fouling the cooler could require removal and steam cleaning or even an internal blockage. Consult Ztechnique for more information on this procedure. 

ZR compressor cooler issues

SERVICE TIP : You may also notice virtually nil DT (delta T) across your cooler when measured with a temperature probe indicating nil flow of water across the cooler.

ZR coolers are harder to examine externally and you should consider removing the HP element side of the intercooler and after cooler assembly to examine the cooler condition. You will almost certainly;y need an intercooler service kit after removal of the cooler to replace the cooler safely and avoid leaking 'o'rings etc.

Material found blocking the cooler externally can be removed with a steam cleaner, however should the material be hard on surface of the cooler tubes you will most likely require removal of the material by a specialist cleaning provider.

In some cases the inner (air tubes) can become blocked and this can render the entire cooler scrap. Its very difficult to clean the internal air side of the intercooler and after cooler tube assembly with any success. 

Consult Ztechnique for more advise and a solution.





Oil Cooler Temperature issues

Oil pressure temperature issues are caused mainly by internal oil cooler blockages ZR and external oil cooler blinding in the case of ZT compressors. Either way this can cause tripping of the compressor and could lead to long term damage of the oil and components like HP and LP element left unchecked.

ZT compressors rely on air cooled radiator type coolers and tend to attract dust and dirt eventually blinding the cooler face resulting in compressor trips. Cleaning the cooler with an air line is a short term solution with a long term solution being removal and external cleaning with a steam cleaner.

ZR compressors rely on Alfa Laval type water cooler oil coolers and are reliable unless the water quality is declining and the result is an internally blocked cooler. These types of cooler are very difficult to clean and should be replaced if after 'back flushing' no significant improvements are witnessed.

If you have issues with overheating of your compressor that can not be attributed to your coolers you should call an expert like Ztechnique to investigate your issues with your ZT ZR compressor.

' Back flushing' is a process of reversing the water flow around the compressor.

Oil pressure issues and causes

Occasionally you can find issues occurring with ZR ZA ZT ZE oil pumps. Oil pressure falling and pressure too high. 

In the case of falling pressure you should check in order

1. Is their oil inside the gearbox.
2. Has the oil filter been replaced on time ?
3. Is the relief valve in good working order
4. Is the HP or LP element noisy indicating any bearing failure or oil injection system failure

these are typical areas to check before removing the oil pump parts and inspecting the condition of each component.

If you need further assistance with any of the above faults consider contacting Ztechnique or one of its Worldwide distributors and seeking assistance.

What is a centrifugal compressor

What is a centrifugal compressor

A centrifugal flow compressor is a form of dynamic compressor that contains a radial design. This radial design operates at a constant pressure rather than a constant flow like displacement compressors.

This page will serve as an overview of centrifugal air compressors, providing you with all the relevant information to help better understand them!

What are Centrifugal Compressors?

Centrifugal air compressors are reliable, efficient and compact devices that allow for the management of air compressor capacity at constant pressures due to their modern like controls.

They typically use gears but some modern configurations of the centrifugal compressor have started to adopt very high speed electric motors to drive the impellers. These configurations are suited to applications that require oil-free air as they operate without a gearbox and its accompanying oil-lubrication needs.

Their performance can be affected by numerous external conditions that may be difficult to control like the change in inlet temperature.

How does a Centrifugal Compressor Work?

Centrifugal compressors draw air into the centre of their rotating impeller using its radial blades. The flow in the centrifugal compressor radially recedes from the driving shaft perpendicular to its motion. This air is then pushed towards the centre due to the centrifugal forces present. The radial movement of air increases the kinetic energy which can be converted into pressure (a form of potential energy) thanks to a diffuser and volute. You could say that the kinetic energy itself causes an increase in pressure, but the process is not that simple.

A diffuser is a stationary component that acts as a radial passage near about the same width as the impeller blades. This primarily works to convert the velocity of the air (kinematic energy) into pressure (potential/static energy). The radial area of the diffuser expands and this expansion causes the desired diffusing effect to occur.

The blades essentially produce a pressure variation very similar to an airfoil of a spinning propeller on an aircraft or wind turbine. The key difference being that the blades are far closer together on a centrifugal compressor. This closeness of the blades and complexity of the design cause a serious alteration in flow between the blades which can be very unsteady,The centrifugal compressors are built in stages, and each stage has a part to play in the overall pressure increase of the system. The stages can vary depending on the application of course.

Centrifugal Compressor Design

Centrifugal compressors are designed to thrive in conditions that have higher capacities due to the continuous air flow through their multiple stages. In most cases, typical centrifugal air compressors have three stages within industrial plants. This is because air systems within plants need on average about an 8:1 pressure increase and centrifugal compressors offer about 2:1 or 3:1 per stage.

Between each stage in the compressor, intercoolers are found and at the exit of the final stage (in this case, the third stage) an after-cooler can be found. The intercoolers cool the air coming out of each stage and remove excess moisture before the air passing into the next stage. This can have a positive impact on the air quality and resulting efficiency of the system. The compressor is mounted on a base that contains:

  • the driver – typically a motor
  • gears – bull gear with pinion gear – these driver the air compressor stages
  • stages – amount vary depending on the application
  • coolers – intercoolers and after-cooler
  • piping – connecting the system
  • valves – inlet guide vanes, blow-off valve, check valve
  • modern controls – in most cases, a control panel

Performance Comparison vs. Other Compressor Types

Dynamics Compressors

As centrifugal flow compressors are a type of dynamic compressor, it is only right to compare them against the other form of dynamic compressor. Now, introducing axial flow compressors.

Axial flow compressors have a far more complex design than centrifugal compressors which results in more difficult manufacturing operations, more components, higher price per unit and significantly higher maintenance costs. As you have learnt from this article, the flow in the centrifugal compressor radially recedes from the driving shaft perpendicular to its motion. On the other hand, axial compressors flow direction is parallel to the axis of its shaft.

Axial compressors are far more suited to designs with multi-stages and have smaller frontal area. Centrifugal compressors can boast difficulties if a multi-stage requirement is desired.

In regards to the ever so important pressure ratio. The centrifugal compressor achieves the highest per stage ratio in comparison to the axial that develops a very low pressure ratio per stage. This leads to the requirement for more stages, which may become a hassle or difficulty.

Positive Displacement Compressors

The positive displacement compressors have a very high pressure ratio when compared against these two dynamic compressors.

Axial compressors hold the best efficiency rating, higher than centrifugal and positive displacement compressors. This is primarily at large capacities because positive displacement compressors are generally the best for small capacities.

Specifically looking at reciprocating air compressors, a type of positive displacement compressor. It can be said that centrifugal compressors typically have a better isothermal efficiency and isentropic efficiency. Importantly, they require far less maintenance than reciprocating

compressors. However, if the pressure ratio is greater than two, it is likely that the reciprocating compressors will operate with far better efficiencies. And although they require more maintenance, they’re a lot easier and cheaper to repair.

Reciprocating compressors require more maintenance than centrifugal compressors due to their multistage operation. Though this may be worth it for a wide array of applications as it is certainly advantageous. Reciprocating compressors are far more flexible and work significantly better with varying pressures.


Centrifugal compressors are best suited for applications above 200 horsepower for reasons stated previously. They have numerous applications across a variety of industries with the most notable being:

  • Pipeline booster services
  • Onshore and offshore gas lift services
  • Chemical plants
  • Gas injection
  • Transmission and storage of natural gas
  • Jet engines
  • Turbojets
  • Turboshafts

How Reliable are Centrifugal Compressors?

Centrifugal air pumps and compressors, like any other type of air compressor certainly undergo faults and may require maintenance and servicing of high quality at times.

They have very complex designs and therefore require great testing to determine their performance before manufacturing. Wind tunnels and advanced computational models are used to determine the designs performance, and therefore can result in more reliable compressors.

They offer high-volume capabilities in relatively compact scenarios and can be extremely reliable compressors when applied properly. This can be said for any of the varying dynamic compressors.

What is a dry screw compressor

What is a dry screw compressor

Oil free screw compressors operate with no contact between the rotors and the casing and are therefore subject to leakage flow through the various gaps. This leads to a reduction in the amount of delivered gas and the overall efficiency. Screw compressor leakage paths are typically categorised into 6 types as described in detail by Fleming et al [1] and schematically presented in Figure 1. The relevant significance of each leakage path will vary depending on the rotor profile and casing geometry; the working fluid and operating conditions; and the type of a screw compressor, dry or oil injected. However some leakage paths generally affect performance more than others. Fleming suggests that the order of influence of leakage paths to the mass flow rate for a refrigeration compressor is 1st - cusp blow-hole, 2nd - the radial clearance between the rotors and the housing, 3rd - the interlobe meshing line gap and then 4th - the gap between the end of the rotor and the casing end plate at discharge. Of these leakage paths the radial and interlobe gaps are directly related to the design clearances, the discharge end face gap - also called axial gap, is an assembly feature while the blow-hole area is an inherent feature of the rotor profile geometry. Fleming shows [1] that the radial and the interlobe gaps have the most significant effect on the indicated power and volumetric efficiency, respectively.

Figure 1. - Leakage pathways in a screw compressor

The obvious solution to increasing efficiency of a compressor is to reduce leakage flows in the radial and interlobe gaps by reducing clearances as much as possible. Modern manufacturing methods allow rotor profiles to be machined to a tolerance of 5 microns [2]. However, consideration must be given to manufacturing and assembly errors of rotors and other compressor elements [3] and particularly to the operating deformations which generally may be larger than the manufacturing tolerances [4]. With tip speeds sometimes significantly higher than 100 m/s for oil free machines, rotor contact can lead to irreparable damage. Therefore adequate clearances are vitally important. Examples of design techniques commonly used to safely reduce leakage gaps while maintaining reliability include the use of rotor tip seals and rotor tapering. Rotor tip sealing strips are designed to allow radial clearances to be reduced because if slight rotor to casing contact occurs the small contact area will ensure it does not result in significant compressor damage. It was claimed in Fleming et al [5] that, if correctly designed, they can even reduce the viscous drag in oil injected compressors. The downside of tip sealing strips is that they add further complexity to the design and manufacture of rotors. Rotor tapering allows for the thermal growth of the rotors in order to maintain safe tip clearance along the rotor length.

Several research reports have been produced to define limitations of how far clearances can be reduced without compromising safety and reliability of a screw compressor. Accuracy of these limits is based on the ability to predict or measure actual operational clearances. Due to the complex pressure and temperature distributions on the compressor rotors and casing as well as the relationship between the operating conditions and compressor performance, this is not a straight forward task. For example, as clearances decrease, leakage flow decreases which leads to improved performance typically resulting in reduced discharge gas temperatures. However, lower operational temperature will increase clearances. A particular challenge when predicting operational clearances is to understand the actual temperature distribution within the compressor. Examples of using numerical methods to calculate temperature distribution on the rotors and casing and thus the change in clearances have been given by Kovacevic et al [2] and by Sauls et al [6]. The former uses Computational Continuum Mechanics to allow simultaneous solution of the solid and fluid domains on a 3D numerical mesh of the actual compressor geometry while the latter uses 1-dimensional simulation of the thermodynamics allowing temperature to be mapped to a 3D finite element grid for each phase of the compression cycle. Both approaches showed good correlation when compared against experimental data.

Leakage flows though internal clearances have a major influence on the performance of a screw compressor. When using numerical models to predict the compressor performance the results will vary substantially depending on the assumptions made about the internal clearances [7]. The ability to accurately estimate operational clearances during the design of the compressor is a key factor for competitive position of the new compressor in the market. With modern rotor profiling methods [8] and flexibility of manufacturing techniques like thread grinding, it is easier than ever to develop bespoke screw compressor rotors tailored to a specific application and economically manufacture them in relatively small quantities. For this approach to be successful the numerical or analytical methods used during the development of new profile will not only need to have been verified against actual performance test data for an existing compressor but also be flexible enough to be applied to a modified compressor design.