PEX Series – Liquefied Gas Pump
The PEX Series ProTech Pumps are unique in the ProTech Air Driven Pump range as they use pistons rather than plungers in the liquid ends. They are correctly described as Double Acting Air Drive with direct coupled Single Ended Double Acting fluid pumps. In this regard, they are very similar to the Haskel Models ATV-4 & ATV- 8 and DTV-4 & DTV- 8. The use of the piston in the liquid end allows for high pressure fluid outlet flow in both directions of the reciprocating pump action thus making the pump double acting and highly efficient. All ProTech PEX Series Pumps use our 160mm diameter air drive reciprocating motor with an 80mm stroke thus achieving much higher flow rates than the Haskel ATV range. The PEX Series pumps are suitable for liquids, gases and vapours – making them the perfect as a liquefied gas pump. The PEX series uses PTFE and Viton seals so has excellent fluid compatibility.
How the PEX Series Pumps Work
To obtain this double acting pump effect in the ProTech PEX Series and the Haskel ATV/DTV Series, a single piston pump is mechanically connected to one end of the air drive motor by way of an interconnecting piston rod. The volume taken up by the piston rod (called the annulus) results in the pump having slightly less pump outflow volume on one stroke than the reciprocating stroke. It also results in the pump having a slightly different stall pressure depending on whether the stall pressure is reached on the “pull” or “push” strokes of the pump. None of this has an adverse effect on the pump’s performance but does give rise to another excellent feature and benefit of this type of pump arrangement.
The PEX series uses “gas-tight” ball checks on the two inlet and outlets which makes them very suitable for pumping gases and vapours as well as liquids. The use of stainless steel and PTFE seals in the wetted areas (liquid pump end) makes them suitable for pumping corrosive fluids including water. By attaching pipework to the bare PEX Pump the two inlets and outlets can be manifolded to become a single port inlet and a single port outlet. Changing the pipework arrangement on the ProTech PEX Series pumps and connecting the outlet of the larger volume section of the pump to the smaller volume inlet, we put the two pumping volumes in series with one another. This, in effect, means the same pump can be used as a 2-stage pump or gas booster.
To achieve this ability to pump gases and vapours Haskel require the use of their more expensive Gas Booster models such as the AGD-4. All PEX Series pumps are suitable for liquids, gases and vapours. They are also capable of drawing a vacuum down to 11.25 psi(absolute) in the 2-stage configuration. Interconnecting pipework can be supplied by ProTech thus becoming packaged systems within themselves. In this guise we refer to these pumps as PEX Extraction Systems.
The PEX Range
There are, currently, two models of PEX pumps both using the familiar ProTech 160mm (6.3″) diameter by 80mm stroke reciprocating air motor. The PEX4-46 has a 4:1 ratio with a 47.55 cubic inch displacement per cycle and a PEX6-25 with a 6:1 ratio and a 28.9 cubic inch displacement per cycle. Both models represent a large improvement in flow rates when compared to the Haskel ATV-4, DTV-4 and EXT-420-2 models which use a 5 1/4” air drive with 2″ stroke.
|Brand||Model||Ratio||Displacement||Separation||Distance Piece||Liquid or Gas|
|ProTech||PEX4-46||4:1||46 cu in||Yes||No||Both|
|ProTech||PEX6-25||6:1||25 cu in||Yes||Yes||Both|
|Haskel||ATV-4||4:1||20 cu in||No||No||Liquid|
|Haskel||DTV-4||4:1||20 cu in||Yes||Yes||Liquid|
|Haskel||AGD-4||4:1||20 cu in||Yes||Yes||Both|
- Transfer at pressure of water, LPG, SF6, Freons and other refrigerant fluids.
- CO2 Fire Extinguisher filling.
- Hydro-static Pressure testing.
- Critical Extraction.
- The extraction of LPG, LNG Freon and Refrigeration Fluids.
- Dust suppression.
This type of air driven pump is used as original equipment on many underground mining machines including models by Ingersoll Rand.
PLEASE NOTE that due to the use of aluminium in the air drive, neither the Haskel ATV nor the ProTech PEX pumps are suitable for underground coal mining applications.
For underground coal mine applications, we manufacture 100% 316 stainless steel pumps under our SiA Pumps brand, for more information please call us on +61 73277 8822.
I first came in contact with High Pressure Air Driven Liquid Pumps in 1964, as a young man employed by Pongrass Industries. Pongrass were one of Australia’s leading manufacturers of compressed air powered valves and cylinders (pneumatics) at that time. Pongrass’ head office was at Botany, Sydney and I was employed by W.O. (Bill) Sundin as his assistant, not long after he had opened up a one-man Brisbane office, a couple of years earlier.
The Brisbane market for pneumatics was limited in those early years and by virtue of Bill being an excellent “bib’n’braces” marine engineer, we became involved in many related products and applications not then strictly referred to as main-stream pneumatics. One those applications was the filling of CO2 fire extinguishers for Wormald Brothers Pty Ltd and the subsequent pressure testing of various pressure vessels used by the firefighting industry.
Bill designed an electric driven CO2 transfer pump which we manufactured in our small workshop situated in the Hedley Park Wool stores, near the Brisbane airport at Hendra. For pressure testing, we used a Madan Airhydropump sourced from H.G. Thornwaites in Sydney. Thus the Madan Airhydropump became the first air driven pressure test pump to be installed in Brisbane.
Bill retired in 1969 and I became the state manager but a lot of water has flowed under the bridge, since then.
Early days of the Air Driven Liquid Test Pump:
Recent research leads me to believe that the Madan Airhydropump was one of the earliest, if not the earliest, commercial product range of this type. A Google search of Charles S. Madan and Company Limited indicates that the company dates back to 1900. The earliest reference to the Airhydropump I can find is 1943 Charles S. Madan and Company, which, in the 1930’s appears to have been involved in brass foundering. The Brass Foundry probably explains why those early Madan pump models had many brass components within the design. Models such as Madan: Junior and Ghurkha come to mind but there were quite a few. The factory was situated in that hive of engineering expertise, Altrincham, Cheshire, England. Madan Pumps and parts are still manufactured by Hydraulic and Pneumatic Services.
The development of the Air Driven Liquid Test Pump, by Charles S. Madan and Co appears to be related to applications arising out of aircraft production during the Second World War. This is interesting because the development of such equipment in the USA, certainly has a connection with the U.S. Aircraft Industry.
1950’s and 1960’s: Competition increases in the Liquid Pump space.
During the 1950’s and early 1960’s California based companies such as Haskel, SC and Sprague, whose founders all knew each other I am told, developed their own versions of air driven test pumps and those brands are still manufactured currently. There was a lot of competition to obtain the business from the Lockheed Aircraft Corporation situated in Burbank, California. I became involved with the Haskel Product Line in the late 1960’s after a visit by Haskel Inc’s CEO, Richard (Dick) Hayman to Pongrass’ Sydney office and the subsequent arrangement whereby Pongrass was appointed the sole Australian distributor for the Haskel Line. I remember this event as Bill Sundin was flown to Sydney to be involved in this decision. Flying to Sydney was a major event in those days.
Haskel also developed both an hydraulically driven and an air driven gas booster product range and this is the subject of a separate article. What is interesting, and also very curious, is that a search of relevant patents shows a patent being awarded to Charles S. Madan and Company in 1978: Patent 4068983. The wording of the patent is also interesting. The patent lists John Francis Perkins and Roy Balme as the inventors but searches of these names only reveal that Mr Balme was a director of Bridge Hydraulics which now appears to have ceased trading. How a patent was awarded so long after the event makes for an interesting later research and possible article.
More recent times: Improved Material Quality & Cost Reduction.
Most of the brands of the early designers and manufacturers of these types of pump, are still available despite numerous corporate take-overs and the like. Many other brands have been released, but the technology has changed very little, if at all, since the 1950’s and 1960’s. The most significant development of recent times is that these pumps are becoming much less expensive while, at the same time, using better corrosion resistant materials as a standard bill of materials. It is in these areas of improved material quality and cost reduction that the ProTech range excels.
Current designs and proto-types are being tested that focus on other areas. In particular, ProTech Pumps is developing a new linear air motor design that greatly increases efficiency. The production of compressed air is energy consuming and expensive and the new design will produce savings of up to 50% on current popular models. Interfacing air driven pumps with electronics is another area ProTech is working on. Such initiatives will allow for very accurate flow and pressure control from other control systems while keeping the inherent advantages of the Air Driven Liquid Test Pump.
About the author
Colin has over 50 years of hydraulic and pneumatic engineering experience in the design, manufacture and sale of pumps and systems for pressure testing and chemical injection. We put Colin’s vast knowledge to good use here at ProTech Pumps in all areas of the business and now we’ve given him his own blog so he can share that knowledge with you too.
Recognising that the application and selection of air driven liquid pumps no longer requires highly specialised, factory-trained technical staff, protechpumps.com removes the costly middlemen and passes on the savings to customers. Adam Stent, General Manager, believes, “By taking a different approach to the market, one that is predominately online, we are able to offer cost savings without sacrificing performance.” He goes on to say, “The performance of our ProTech Pumps range is comparable to the big brands like Haskel and Maximator but without the hefty price tag.” Being predominately online doesn’t mean there isn’t any product support. Selection guides, comparison charts, application resources and, coming soon, live webchat combine with more traditional phone and email support to deliver a quality experience. Plus ProTech Pumps offer FREE Standard Shipping, Australia-wide on all online orders.
Buy Liquid Pumps Online
The protechpumps.com webstore makes it easy to view, compare, select and buy a complete range of high performance pumps, gas boosters, air amplifiers and valves & fittings online. In addition, the ProPak range (available to buy online) as well as customised skid design and manufacture cover all your high pressure system requirements from portable pressure test systems to workshop based testing facilities.
About ProTech Pumps
ProTech Pumps is a Solar Injection Australia brand, which has more than 50 years’ experience in hydraulic and pneumatic engineering across design, manufacture and sales, particularly of pumps and systems for pressure testing and chemical injection. Solar Injection (SIA) has manufactured high quality chemical injection pumps (CIP) in its Brisbane, Australia manufacturing centre for nearly 10 years. SIA’s roots go back over 40 years, mainly as technical distributor for Haskel Air Driven Liquid Pumps, Gas Boosters and High Pressure Valves and Fittings.
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