Sprague PowerStar 4 FAQ
What It Does
The Sprague PowerStar 4 is a positive-displacement hydraulic pump driven by compressed air. It uses relatively low air pressure, acting on a large area piston, to produce high liquid pressure using a small area output piston. Pumped media can include water, oil and most corrosive chemicals. These pumps are rugged, industry-proven, low maintenance and are non-arcing and non-sparking which makes them a good option in hazardous or confined areas.
How It Works
When air pressure is applied to the Sprague pump, it reciprocates rapidly as it initially pumps liquid. As the liquid pressure increase sand nears the desired level, it slows to a stop due to the liquid pressure balancing the air pressure. This liquid-air pressure balance is maintained indefinitely in a holding condition with minimal energy consumption and without increase in fluid temperature or parts movement. (A motor-driven pump in a holding condition must continue running to maintain apressure level. Excess liquid must be bypassed or recirculated back to the reservoir, resulting in energy-loss, heat build-up, and the need for bypass components and a larger reservoir.)
Uses
The Sprague air-driven pumps can produce pressures in excess of 30,000 psi and are often used for hydrostatic testing of hoses, pipes, valves, fittings and other hydraulic vessels and products. They are also commonly used to deliver high pressure liquids required by production machinery for holding, clamping, forming, shearing and punching. A typical application is a hydraulic press where
long holding cycles are necessary or where a short stroke and high force are required. High and low volume Sprague P4 pumps can be combined to produce an economical combination of both high speed and high force. Because Sprague air-driven pumps are compact, they can be installed directly on individual machines or test equipment as the direct power source.
Pump Options
PowerStar 4 pumps can be ordered in single or double ended version. The double ended version pumps have about the same output pressures (slightly higher) but flow is 1.6 times the rate of single ended pumps. The single ended pump can be ordered in the standard version or in the Separation version which includes a kit that ensures separation (no cross contamination) of the air and media that is being pumped. (Double ended pumps come with separation kits already installed.) The pumps can also be special ordered with Viton, EPR, Neoprene or other sealing material for the liquid end of the pump as needed. All pumps can be ordered with air controls (includes filter, regulator, gauge and shut off valve) and/or with a liquid control (includes manifold, gauge and bleed valve).
Frequently Asked Questions
Q. What is the difference between single ended and double ended pumps?
A. Double ended pumps have the same single air piston module but use two liquid pump modules on each unit, instead of just one. This does not change the maximum output pressure much (slightly higher) but increases the flow rate to 1.6 times that of a single ended pump.
Q. Can I order a double ended pump with two different ratios, one on either end, so that I have both high flow and high pressure on the same unit?
A. No. You have to have the same ratio on each end of a double ended pump otherwise the pump stops cycling once it reaches the maximum pressure of the high
flow (low pressure) end. A common solution, though, is to use two pumps - one high volume and one high pressure in parallel.
Q. MODEL NUMBER - Where do I find the correct model number on my pump?
A. The model number for the complete pump is on the vertical surface of the larger portion of the pump. (The other sticker(s), on the horizontal surface(s) of the pump, only gives the model number of half the pump - the liquid half.) See Label photo...
Q. What kind of liquids can I run through these pumps?
A. The liquid portion of the pump is made of stainless steel and the pump seals are available in multiple options which means that most liquid can be readily accommodated.
Q. How compact are these pumps?
A. A single ended pump is 6"h x 6 1/2"w x 8"l and weighs 16 lbs. A double ended pump is 6"h x 6 1/2"w x 10 1/2"l and weighs 21 lbs. You can see drawings of the pumps on the data/spec sheet.
Q. How much control do I have over liquid output pressure?
A. The output pressure is basically infinitely variable within the pressure range of that pump. Increasing the air pressure will increase the liquid output pressure a proportional amount. Varying the air pressure on 10:1 pump anywhere from 10 psi to 100 psi, for instance, will give you a resulting liquid outlet pressure of anywhere from 100 psi to 1000 psi.
Q. I can control the liquid outlet pressure by adjusting the air pressure but can I control the liquid flow rate too?
A. Yes, you can. You accomplish this by changing the air flow rate - this will adjust the liquid flow rate.
Q. What is a "separation" kit and will I need to order my pump with this option?
A. Most applications do not need a "separation" kit. If your application demands that there not be "cross contamination" between the air (pumping gas) and the liquid (pumped media) in the case of a seal failure, then order the separation version. It has an extra kit added to the pump that ensures separation of the two medias. This means that a leak on either the liquid side of the pump or the air side will not result in "contamination" of the other side. A drain port in the bottom of the pump between the two halves allows any leaked media to be routed away as needed in your application. Double ended pumps come with this option as a standard feature.
Q. Will adding a "separation" kit change the pump dimensions or operating performance?
A. No, it will not.
Q. Do I need to lubricate the compressed air that I use to run this pump?
A. No. You do not need to run lubricated air through these pumps. They have self-lubricating air piston seals suitable for clean room usage.
Q. How much air will this pump use?
A. It depends on the air pressure required and on the pump flow rate. If the pump is holding maximum liquid pressure with no flow, then there is no air usage. The charts on the specification page show actual usage at different air pressures and liquid flow rates. Maximum air usage at 100 psi with maximum liquid flow (low liquid pressure) is 50 SCFM.
Q. How low an air pressure will these pumps run at?
A. As low as 5 psi.
Q. If I don't have much air flow will the pump still work?
A. Yes, it will still work fine, but at a slower rate as long as there is enough air to cycle the internal air valve.
Q. Do the higher pressure pumps use more air?
A. No. All the pumps have the same air module. Higher pressure pumps use the same amount of air but have lower liquid flow rates.
Q. Does this pump require positive liquid pressure on the inlet side of the pump (flooded suction)?
A. Some do and some do not. Contact us if your application does not have positive pressure at the inlet.
