Portable hydraulic tools are increasingly being relied upon for jobs that once involved backbreaking and hazardous manual labour. Selecting the right pump for the job is critical to the efficiency and safety of these powerful tools.
Many plant maintenance tasks,such as tightening or loosening bolts, cutting rusted nuts, spreading flanges,or lifting and positioning equipment, can be made easier by using these powerful and precise time-savers.
But because of the varying operating ranges and capabilities of these tools, many factors have to be taken into consideration when deciding how the tool is to be powered, says the leading global high-pressure (700 bar) hydraulics specialist Enerpac, the products of which are widely available from a well established distribution network throughout Australia.
Traditionally, users of hydraulic tools have been able to choose from three main pump power methods: hand,air, or electric. Each power source offers distinct advantages.
Hydraulic hand pumps are probably the easiest and least costly type to use. They are usually the most inexpensive solution to portable hydraulic power source requirements.
They are ideal for infrequent use of small to medium size hydraulic tools and particularly useful on remote sites where power sources are not available.
In situations involving hazardous (classified) locations, a hand pump may be the only choice, because it does not rely on a power source that could produce a spark.
Hand-operated pumps come in a wide range of sizes from small, single-speed models weighing less than 5kg, to large, metal, two-speed units weighing close to 45 kg. Units are available with valving for both single and double-acting tools and with oil capacities up to eight litres.
Specifications for hand pumps should meet certain criteria: system oil capacity, type of valving, and fluid compatibility.
Because they are typically used for short, non-repetitive applications, duty cycle is usually not a primary concern.
The main limitation with hand pumps is evident in the name. Because it relies on hand effort, operator fatigue may occur. Also, because one hand is needed to operate the pump,leaving only one hand free, efficiency and convenience can be reduced.
A new hand pump from Enerpac – the ULTIMA series of steel hand pumps - are designed for easier and safer operation, as well as extended life.
These versatile hand pumps are ideally suited for rugged applications, where durability is of utmost concern.
The series now features an innovative design that provides greater ease-of-use.Handle effort is reduced by up to 20 percent in the ULTIMA steel hand pumps without compromising speed or performance.
The pumps’ innovative bypass system further reduces loads often created by two-stage pumps. By incorporating the new Power Push handle grip and linkage design, loads are better distributed further reducing felt load while pumping – minimising operator fatigue.
But while hand pumps are very portable, they may not be suitable for use in confined areas such as catwalks or on ladders, where users may not be physically able to generate the full amount of power needed. Another factor to consider is that these pumps must be placed on a relatively flat surface during operation.
Air-operated pumps, like hand pumps, are relatively simple to specify, and come in a wide range of sizes.They feature increased performance compared to hand pumps and, when far enough from a compressor, can be used in an environment where the spark from an electric current could otherwise pose a hazard. In addition, most are relatively lightweight and portable.
Reciprocating pumps are the most popular because they are a cost-competitive alternative to hand pumps while offering better performance. Reciprocating air pumps are usually single-speed units. They feature high flows at low pressure, because the air motor runs faster under reduced loads.
When high flow is needed, a dual version of the reciprocating air pump can be used. It consists of two pumps linked together, one for high flow, the other for high pressure. This arrangement allows the high-flow unit to stall at high pressure and does not require an unloading valve.
When greater levels of performance are required, a rotary air pump can be specified. This pump consists of a rotary air motor driving a conventional hydraulic pump. This style of pump tends to be heavier, noisier, and requires more air than the reciprocating version.
A versatile option is presented by Enerpac’s 700 bar XVARI XA air-over-hydraulic foot pump, which enables finer and safer control of tasks while completing jobs up to twice as quickly as conventional pumps. It features tremendously high oil flow, with its rotating air motor and rotating two-stage pump element giving twice the oil flow of conventional air-driven pumps.
This radically different technology– offering variable oil flow and fine metering for precise control – is coupled with ergonomic two-pedal control of advance and retract functions for time-efficient and safer hands-free operation with less operator fatigue and increased stability.
The most important consideration when specifying either style of pump is to ensure that the available air supply is sufficient. All air pumps rely on a certain air flowrate, stated in litres a minute (or standard cubic feet per minute, scfm), to provide maximum performance. If the supplied airflow rate is unknown, a rule of thumb is that one horsepower at the compressor supplies 5 scfm (standard cubic feet a minute, approx 142 litres).
Air-operated pumps are ideal for use in facilities where pneumatic lines are installed and easily accessible. Air-operated pumps can be more expensive to run compared with electric pumps, because compressed air can be a less efficient way to power tools.
The second most common type of high-pressure pump, after hand pumps, is electric models. They are versatile because users can choose from many options, such as motor type, valves and actuators, heat exchangers, and operating voltage. Because of the options available, they are the most difficult to specify correctly.
Besides the primary considerations for pump selection (such as size, valving, reservoir capacity and voltage), the required duty cycle and electric motor have to be carefully reviewed.
Duty cycle is the amount of time the pump runs and at what percentage of full load. The majority of high-pressure (10,000 psi) hydraulic pumps are not designed for high duty cycles. Applications that require pressures above 5000 psi for periods longer than one hour should use pumps with coolers to maintain oil temperatures at 65C (150F) or less.
There are two electric motor choices: induction and universal. The choice depends on the application.
Induction motors are ideal for high duty cycle applications, because they are designed to run for long periods of time with long service life and at low noise levels. Noise is an important factor when working in confined spaces.
Induction motors also tend to be heavier, which is why they are most prominent in facilities where a high production, stationary pump is required.
A critical consideration when specifying induction motors is a very stable source of electrical power. If line voltage drops as little as 10 per cent, the motor could be severely damaged. Situations where electrical power is supplied by a generator through an extension cord may not be the best for this type of pump.
When an application requires the speed and performance of an electric pump, but the power source and portability are factors, then a pump with a universal motor should be considered. This type of motor features light weight (about 25 per cent less than an induction motor), high power-to-weight ratio, and the ability to run on less-than-ideal electrical power. Universal motors can produce full torque on as little as 50 per cent of rated line voltage.
Enerpac’s ZU4 series portable hydraulic pumps feature a powerful 1.25kW universal motor coupled with a totally new pump element design that reduces oil flow turbulence, producing an industrial workhorse with fewer moving parts and less friction. Special models can be configured for particular applications,including bolting.
Similarly, the ZE series of 700bar electric pumps from Enerpac is engineered to save power and increase reliability by reducing the number of moving parts it incorporates, enhancing flow characteristics and reducing friction.
The high-efficiency design of the ZU and ZE series electric pump has higher oil flow and by-pass pressure, runs cooler and requires 18 percent less current draw than comparable pumps.
Special purpose torque wrench pumps are also available, designed to deliver optimal productivity and reliability with simplified operation and maintenance.
The TQ-700E Classic 700 bar electric pump features a brushless motor designed for continuous usage and simplified maintenance in high cycle applications and demanding environments. These include wind farms, erection of turbines, installation of gearboxes, maintenance of pressure vessels and pipelines, bolting of tower foundations and numerous other tasks within industries such as mining and energy, oil and gas,construction and manufacturing and maintenance of pressure vessels and pipelines.
The pump – which weighs under 30kg dry and operates well from generators - is also ideal for mobile plant workshops on mine and resource sites, and field maintenance for dragline,shovel and heavy plant repair.
Another recent innovation in pumping technology is represented by Enerpac’s XC Series cordless pumps, which offer the performance capabilities of an electric or pneumatic powered pump with the convenient portability of a hand pump.
The all-new line of cordless powered pumps provides a portable, cost-effective solution for remote locations that delivers the speed, power and longevity of a corded pump.
Designed to satisfy the need for a long-lasting pump that can be used in hard-to-access areas, XC-Series cordless pumps are constructed of lightweight materials,equipped with a powerful, one-half horsepower motor and feature 28-volt, Lithium-Ion battery technology.
With its bladder reservoir, Enerpac’s cordless pumps eliminate venting and offer leak-free operation in any orientation. Plus, the overall body, handle and trigger have been ergonomically engineered to maximise ease-of-use and portability.
Pump Selection Guidelines
- Determine appropriate ratings for oil capacity, maximum operating pressure,cycle duration and frequency, flow rate, and valving.
- Compare overall cost. Increased productivity and reduced manpowerrequirements should be considered.
- Check safety and ease of use. Portability and weight determine how muchstrength and dexterity the operator must have. Sound levels should be low.
- Check power requirements. Available power often dictates the type ofpump used.
- Match tool speed. As pump size increases, power requirements escalate.Pumps should be sized to the required speed and not beyond.