To ensure a problem free installation, check requirements in the following areas.
What is the medium? If you are actuating cylinders or jacking, mineral oil is most likely.
Is there any reason not to use it? Fire risk, environmental contamination, disposal problems, cost of the medium and internal contamination may be reasons to look carefully and look at alternatives. We have expertise on water hydraulics and alternative media. Many of our pumps are multi-fluid
What pressure? On lower cost pumps for oil hydraulics 200 bar is widely used. On jacking equipment, a whole industry is based on 700 bar. There is a trade off on cost, mass and safety in selecting a working pressure. For any pressurised system, safety is paramount. Our equipment covers the range 1 bar to 1000 bar.
What environment is the equipment being used in? A saline environment requires substantially different materials to a machine shop. A hazardous environment with an explosion risk has its own specific solutions. It is essential to know. Painting may be a solution to a corrosive environment, but is no fix for the risk of hydraulic components corroding. We have expertise on corrosion resistant and explosion proof/ATEX equipment.
Temperature range. Beware low operating temperatures or large temperature swings. Many parts of the world have them! There are implications for fluids and materials. We have experience on high and low temperatures.
Do you need a pump in a cardboard box or various components forming a hydraulic circuit to do a job? If you can buy a pump with various other circuit components such as relief valves and release valves integrated, this will cut out pipework and fittings. Buying a pump with extra features which are not required in the circuit may confuse the operator. Our equipment is modular and auxiliary components can be added easily and inexpensively.
Are there any specific requirements? A very low leakage pressure test or load holding double acting cylinder have very specific requirements. For example, for very low leakage, poppet check valves with extra sealing would be preferable to simple and cheap ball check valves as used in industrial oil hydraulic components. We have expertise in identifying the correct components in a system
What service life would you expect? In a world of throw away equipment, there is still equipment which can be serviced, with the life extended by replaceable valve seats. We offer low cost service kits for our pumps.
Contact us to discuss the best hand pump for your application.
Pressure (or hydrostatic) testing is a key production process. Irrespective of how much of a safety factor has been designed into a product or how closely controlled a process such as welding may be during production, there is no substitute of carrying out a pressure test to a set pressure for a certain period on a given fluid. This is the only way to ensure there is “no leakage or permanent deformation.”
How?
On low pressures, shop air or other gases in conjunction with leak testing by immersion in water or leak detection spray (or detection equipment) can be very effective and easy. Depending on the volume of the system and failure mode, gas testing becomes dangerous.
Fluid testing involves prefilling the unit to eliminate air then raising the pressure. Testing on water has the benefits of low cost, external cleanliness in a workshop, internal cleanliness with no degreasing required, water being low viscosity, fairly searching and safety. Where there is a risk of something failing, there is always the need to work safely and consider system volume, failure mode and safety of personnel and property. Consider also the ability to record the pressure reached, for example by using a drag pointer pressure gauge. Some systems may specifically need testing on media such as mineral oil or kerosene. Residual water in such a system or component may not be acceptable.
Various types of pumps can be used. At low pressure mains water may be adequate, bye-laws permitting. A hand pump is highly cost effective, especially if large systems are pre-filled. An air driven pump (using an air motor to drive a fluid pump) can be used on its own or built into a hand pump unit and will take the pumping effort out of the task. The cost is significantly higher than a hand pump. An electric pump can be used, although for many users the safety risk on an electric installation and high cost on higher pressure water hydraulics make this far from optimum.
Contact us to discuss pressure testing.
For pressure testing, our normal advice is to look seriously at water as a medium before moving to oil or other fluids. Testing on water has the benefits of low cost, external cleanliness in a workshop, internal cleanliness with no degreasing required, water being low viscosity, fairly searching and safety. There are few ancillary components in the system, so little cost implication on having to buy in water compatible components.
Water Hydraulic Applications
It would be fair to say that for the vast majority of power hydraulic applications, people will only move away from mineral oil because they have to for various reasons. There are a whole spectrum of fluids available, all having various pluses and minuses. Some water glycols offer properties very close to those of oil although check out the technical data carefully. Suppliers such as Vaughan have considerable expertise. Water glycols are also used as low viscosity offshore control fluids and these have their own characteristics. A further specialist class of fluids are phosphate esters such as Monsanto “Skydrol”, used as a fireproof hydraulic fluid for the aerospace sector. Finally, water is another option. We have considerable expertise on alternative fluids, so please ask.
Key issues to address when looking at alternatives to mineral oil are:
Inherent safety – You are using a fluid under pressure. Consider the fire risk if there is a leak. Also consider that some of these fluids are quite poisonous.
Cost – Some glycols may well be more expensive than mineral oil, whereas tap water is the perfect medium for low cost.
Corrosion – Materials of the equipment may need to be changed in response to different fluids. For pure water, stainless steel and bronze would be the best choice for a long service life. Anodised alloy can also provide a long service life, although brass should not be used for fittings (due to galvanic corrosion). Long term use of water glycol (such as anti-freeze) in conjunction with anodised alloy is also a concern for some industries due to corrosion. Hard water has its own scaling problem.
Lubricity – Pure water has poor lubricating properties compared with mineral oil, so components must be selected to take this into account. Composite seals used in many of our hand pumps work very well on water, but any bought in components using O rings in a dynamic sealing application can suffer. If other fluids are being assessed, the lubricity can sometimes be quite difficult to evaluate. Certainly, premature failure due to seal wear can limit the application of these alternative fluids. Some offer properties similar to oil.
Viscosity – Some alternative fluids offer viscosities comparable with mineral oil, but others are as thin as water. Mainstream hydraulic components for mineral oil often just cannot cope with thin fluids and specialist valves have to be sourced. Ball check valves seating on metal seats are generally not suitable for thin fluids and poppet valves should be considered. Relief valves need to be soft seat of similar construction. Directional control valves are unlikely to be mass market spool valves as they are simply unsuitable for water or low viscosity fluids.
Temperature range – Do not neglect the fact that water freezes! If you have to use additives to prevent freezing, there will be another set of decisions to be made.
Many of our pumps were designed for use on water so are true multi fluid units. Please contact us.
A double acting pump is a hand pump which pumps on both the ‘up’ and ‘down’ strokes of the handle. It will displace or move X cc of oil per double stroke, with half being shifted when the handle is pushed down and half when the handle is lifted.
Not to be confused with pumps to control single acting and double acting rams.
For some sectors of the hydraulic industry, “single acting” describes a pump which has a single pressure outlet and is suitable for operating single acting cylinders. It would probably have a hold/release valve (needle valve) for lowering the cylinder by returning the pressurised oil back to tank. A “double acting” pump would describe a pump with a directional control valve built in and two pressure ports to allow a double acting ram to be controlled. Move the control valve one way and the cylinder extends and move it the other way and the cylinder retracts.
Contact us to discuss the best configuration of hand pump for your application.
Contact us to discuss the best configuration of hand pump for your application.
You would opt for a two speed pump when there is a requirement to prefill a system or move a large actuator at low pressure. The system then has to be raised to a high pressure. Clearly, pumping a small volume of oil over a large number of cycles would take a long time, although the hand load would be very low for the bulk of the cycle. If the maximum pressure is not very high (say 200 bar), it is invariably cheaper to opt for a single speed, double acting pump than a two speed single acting unit. Two speed pumps are always single acting designs. The arithmetic is easy to work out for specific applications, so contact us us if you need help.
Contact us to discuss the best configuration of hand pump for your application.
Contact us with your application.
Contact us with your pressurised inlet application.
Contact us with your flow control enquiry.
Contact us with your enquiry for special seals.
Micropac® is the registered trade mark for our pumps and associated products.