What is a Hydrostatic Test Pump? A Review of Parts and ...

Learn the key hydrostatic test pump components and considerations

As the force behind hydrostatic testing, hydrostatic test pumps deliver peace of mind that water-based fire protection systems won&#;t leak during use. They ensure that piping set-ups will perform under pressure during a fire.

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In previous blogs, we&#;ve dug into requirements for performing hydrostatic tests and explored:

This time, we&#;re getting back to basics: explaining what a hydrostatic test pump is, its important parts, and how it works.

If you&#;re shopping for a hydrostatic test pump, feel free to skip directly to our selection of Triple R pumps. QRFS carries the lightweight and versatile Tru-Test models (250 psi/2.2 GPM) and more powerful HT-454 (400 psi/3.0 GPM), HT90E, and HT89A models (both at 300 psi/3.0 GPM).

When hydrostatic testing of fire protection systems is needed

A qualified fire protection ITM professional uses a hydrostatic test pump to force water into a fire protection system at high pressure. The test offers reassurance that piping was assembled correctly, that damage or corrosion hasn&#;t caused weaknesses to develop, and, in the case of systems that have them, that the Fire Department Connection (FDC &#; also referred to as the Siamese Connection) can withstand high pressures.

Testing occurs at the lowest access point in the system. Inspectors visually examine the pipes, joints, and fittings for leaks and monitor gauges to ensure readings stay within 5 PSI (pounds per square inch) of the specified test pressure. Sometimes, significant drops only indicate a faulty gauge or a faulty pump&#;but they can also reveal a potentially serious problem with system integrity.

The National Fire Protection Agency (NFPA) requires hydrostatic testing of commercial fire sprinkler systems when they&#;re first installed and whenever system modifications involve more than 20 sprinkler heads. This &#;acceptance testing&#; must be conducted at a minimum of 200 psi for two hours in both wet and dry sprinkler systems. Small, subsequent modifications can be retested at normal working pressure, but larger revisions must be isolated and proven to tolerate high pressures.

For residential sprinkler systems, hydrostatic testing is only required at working pressure when the system is installed, according to NFPA 13D: Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes. There&#;s one exception: if the system has a fire department pumper connection, it must follow the guidelines for commercial systems.

Testing requirements for standpipe systems are perhaps the strictest. All standpipes must be tested prior to system acceptance. Certain systems must also undergo full hydrostatic tests every five years, including manual wet standpipes not part of a combined sprinkler/standpipe system, manual dry standpipes, and semi-automatic dry standpipes.

For a deeper look at when, where, and how hydrostatic testing is required, read our previous blog:  &#;What is Hydrostatic Testing of a Building&#;s Fire Protection System?&#;

The technology behind the test: hydrostatic test pumps

Hydrostatic test pumps can be used to pressure test various water systems in residential and commercial buildings, from sprinklers to plumbing lines. Core features are shared by all test pumps, but power, durability, portability, and control can vary greatly among models.

Most standard hydrostatic test pumps are electric. Although they generate less speed and horsepower than larger gas-powered pumps, they produce plenty for most life safety applications. Many inspectors prefer the convenience of plugging in an electric pump instead of messing with fuel. Electric pumps also eliminate concerns about fumes if used indoors or in other enclosed settings.

Triple R&#;s small-but-powerful Tru-Test pump can even be purchased with power hook-ups that can run off of a car battery, making it possible to use electric pumps in unfinished buildings without working power.

Larger, more powerful, gas-powered pumps pressurize systems faster and fill them with water more quickly than electric pumps. They are typically reserved for bigger jobs with bigger pipe, such as a standpipe test in a very tall building.

When selecting a pump specially designed for fire protection systems, the basic criteria boils down to this: how much pump you need in terms of the maximum pressure in PSI and volume in gallons per minute (GPM)&#;and the pump&#;s power source, which can be gas, electric, drill-powered, or a hand pump. Essentially, any pump that can maintain 200 psi (or 50 psi higher than a maximum working pressure that exceeds 150 psi) can adequately perform a hydrostatic test.

But while pressure shouldn&#;t be discounted, zeroing in on the right GPM can save time and money by determining how long tests will take. The higher the GPM, the faster the system can fill and/or pressurize. Triple R Specialty explains that a pump rated for 2.0 GPM at a max pressure of 500 psi will take twice as long to complete a test as a pump rated for 4.5 GPM at a max pressure of 400 psi.

Test pumps powered by hand or drill tend to have GPMs of less than 2.0, making them a less common choice for hydrostatic testing. Many contractors also avoid the inconvenience of needing to hand pump or squeeze a drill&#;s trigger &#; and having to wait longer.

Other important criteria that factor into which pump inspectors should use include:

• Diameter and length of the pipe being tested. A small, residential sprinkler system won&#;t take nearly as long to achieve test pressure as a big standpipe system.
• The type of system and the natural pressure of its water source. It goes without saying that it&#;s going to take longer to fill and pressurize a manual dry standpipe vs. a manual wet standpipe. Similarly, a modified wet sprinkler system that&#;s fed by a city water supply may only naturally generate about 50 to 80 psi of pressure.
• The building&#;s size and height. NFPA knew what it was doing when it specified running the test at a low point in the system but also checking test pressures at system high points. Gravity on Earth is a constant, after all.

The main components of hydrostatic test pumps

The pump

Most hydrostatic test pumps rely on piston- or plunger-type pumps that work best with pressurized water supplies. In order to use them with a non-pressurized water source, starting a gravity feed&#;essentially, using gravity as the pressure source needed to flow water into the pump&#;is typically enough to create positive flow. Simply place the pump at a lower elevation than the container holding the supply of water, turn it on with the priming valve open, and let gravity do its work.

In newer models, the pump is often attached directly to the face of the motor&#;eliminating the shaft common in older machines. This improvement leads to fewer moving parts, less maintenance, and lower overall weight.

The power source

Hydrostatic test pump motors generally rely on three main power sources: battery power, plug-in electric, and gas. Motor size, or horsepower, is determined by the amount of pressure and volume required.

Here&#;s a word to the wise: For plug-in electric and battery-powered pumps, don&#;t forget to check whether the power source meets the motor&#;s electrical requirements. That includes any voltage, phase, hertz, and amperage requirements noted by the manufacturer. It&#;s also important to check whether the pump&#;s parts have enough oil and any other needed fluids before testing begins, including the engine crankcase, gear reduction, and gas tanks.

Bypass/pressure regulator

Fire protection systems&#;especially small ones&#;can pressurize very quickly. To avoid damage, some pumps, such as Triple R&#;s HT-89A, include pressure regulators that keep pressure in check without minute-by-minute monitoring.

Regulators can be preset to close off the water supply after detecting that the outlet pressure has hit a specific number. A full-flow bypass then diverts water directed at the outlet hose back into the pump itself.

But while pressure regulators are a useful fail-safe that enables contractors to focus on more important tasks than continuously monitoring system pressure, it&#;s still wise to check in on the pump. Friction from recirculation causes water to become increasingly hot, which can damage the pump if the regulator runs for too long. What counts as too long can vary from a few minutes to an hour, so be sure to check your manufacturer&#;s recommendations before performing a test.

On a related note, hydrostatic test pumps generally employ two methods of maintaining system pressure after the supply line or outlet hose is disconnected. Some pumps close off the pressure using a manually operated valve that&#;s situated at the supply line. Others rely on an in-line check valve that activates automatically when water flows in the wrong direction, as happens when a pump shuts off.

The gauge

Hydrostatic test pumps include a gauge that indicates the pressure supplied to the system. Read this carefully: that&#;s different from system pressure, which is measured by a separate gauge.

A test pump&#;s gauge must be capable of reading up to two times the maximum pump pressure. Put simply, if the pump is rated for 300 psi, the gauge must be able to read at least 600 psi. Generally, the middle of the scale on the gauge offers the most accurate readings.

Vibration is the leading cause of gauge failure. Just like any other pump, moving components on hydrostatic test pumps pulse, vibrate, and generate heat when used as intended. Over time, these forces can damage a gauge&#;s sensitive parts like links and pivots. Eventually, permanent damage and inaccurate readings can result.

The best hydrostatic pumps rely on a gauge filled with a liquid such as silicone or glycerin that help stabilize its needle. Liquid-filled gauges also limit the build-up of condensation, lubricate moving parts, and guard against sudden changes in temperature.

Watch this video to understand the damage vibration can wreak on a gauge&#;s internal components:

Of course, liquid-filled gauges do present some downsides. Dry models don&#;t suffer leaks and never need to be refilled. They can also operate at temperatures as low as -40°F &#; although the -4°F temperatures permitted by most liquid-filled gauges are adequate for hydrostatic test pump applications.

Pump hoses and electrical cords

Test pumps come equipped with electrical cords and hoses that provide the flexibility needed to connect to a fire protection system during testing. Long lengths of cable&#;like the 25 feet included with Triple R&#;s 12-Volt Tru-Test&#;stretch over long distances, making it easier to connect to a battery in a parked vehicle. Other electric pumps come with shorter lengths of cord&#;most often, six feet&#;that can be combined with standard extension cords if needed.

Hydrostatic test pumps rely on outlet and inlet hoses to move water from the supply source to the system that&#;s being tested. Outlet hoses, designed to withstand high pressures, connect pumps to the fire sprinkler or standpipe system.

Inlet, or supply, hoses, usually use basic garden-hose connections to connect the water source to the pump. Longer lengths of supply hose may collapse during suction, so a sturdy, short hose will offer better performance than a full-length garden hose. To minimize the risk of pump damage or clog-induced flooding, supply hoses also typically feed into a suction-side strainer that blocks debris from the water supply.

Different manufacturers supply different hose lengths with their pumps. Reed&#;s electric hydrostatic test pumps include 15 feet of outlet hose, for instance, while Triple R supplies 10 feet of quick-disconnect outlet hose with all models and 5 feet of supply hose with the HT-454 and Tru-Test pumps.

Quick-disconnect couplings feature a one-way valve that allows the hose to easily separate from the pump, making it easy for fire protection professionals to verify that the piping can maintain pressure on its own. But with this advantage comes a minor flaw: the threaded end that connects to the system is smaller than the 2.5-inch NPT-threaded swivel found on most FDCs, where many systems are tested. When those couplings are used, additional reducers or adapters will be needed.

Contact us to discuss your requirements of hydrostatic hose testing equipment. Our experienced sales team can help you identify the options that best suit your needs.

Pump materials

Weight plays a major role in choosing a hydrostatic test pump, impacting how easy it is for contractors to move around job sites. Generally, the more powerful the machine, the more it weighs. Large-dimension pumps may require two people to carry them and are often mounted on wheels.

Even so, the material used to mold pump parts can create major differences in weight and size between otherwise comparable machines. Pumps rated between 220 psi and 500 psi generally provide enough pressure for fire sprinkler and standpipe testing applications, but the most portable pumps deliver that power at a weight that falls below 40 pounds.

The lightest pumps incorporate aluminum components that weigh dramatically less than parts made from other metals. A cubic foot of aluminum is roughly three times lighter than the same volume of copper, iron, or steel.

For instance, Triple R&#;s kit-style Tru-Test pumps weigh only 22 pounds&#;including its protective metal case. Such easy portability packs the power of 250 psi and 2.2 GPM.

Aluminum construction also places the manufacturer&#;s more powerful electric models among the lightest choices in their PSI/GPM class, with the HT-90E weighing in at 32 pounds (300 psi/3.0 GPM), the HT-454 weighing 34 pounds (400 psi/3.0 GPM), and the HT-89A weighing 35 pounds (300 psi/3.0 GPM).

By comparison, hydrostatic test pumps by other manufacturers typically weigh more, from Reed&#;s EHTP500 (37.5 pounds and 500 psi/2.0 GPM) to Rice&#;s EL1A (74 pounds and 500 psi/3.0 GPM), although that one also includes a roll cage.

Of course, lighter weight isn&#;t the only advantage of using aluminum parts. Aluminum-based pumps are also more resistant to damage from corrosion and freezing. Casings on older models crafted from cast iron or other metals have been known to crack when vibrating in freezing temperatures.

Brass piping can also help keep weight down and corrosion resistance up in hydrostatic test pumps, compared to traditional cast iron or galvanized steel options.

How do all these parts work together?

Basically, all hydrostatic test pumps work the same: pumping water into a piping system at higher-than-normal pressure to ensure the system is drip-free and there&#;s minimal risk of failure. Note that the following steps only represent best practices, and manufacturer&#;s instructions should be followed for specific pumps.

To start the test, inspectors must first make sure all lines are filled with water and any air is removed. Opening the inspector&#;s test valve &#; or another valve on the end opposite the water input &#; will allow air to escape.

Connect the test hose to the system, and then to the hydrostatic test pump. Turn on the water to the pump, and then turn on the pump. Alternately watch the gauge and the pipes, checking for visible leaks and monitoring system pressure. After the desired pressure is reached, turn off the pump and disconnect the test hose.

For step-by-step instructions, check out our previous blog on using hydrostatic test pumps.

Hydrostatic test pumps ensure the integrity of fire protection systems

Hydrostatic test pumps make it possible for fire safety inspectors to test the integrity of water-based fire protection systems. They help identify problems that can be easily missed during a visual inspection, delivering assurance to property owners and fire safety officials that a system will perform as intended during a fire.

If you&#;re shopping for a hydrostatic test pump, be sure to browse our selection. QRFS carries the best pumps in the business, including lightweight and versatile Tru-Test models (250 psi/2.2 GPM) and more powerful HT-454 (400 psi/3.0 GPM), HT90E, and HT89A models (both at 300 psi/3.0 GPM).

For any other Triple R Specialty pump you may be interested in, or to find out more information about pumps or hydrostatic testing, give us a call at 888.392. or .

This blog was originally posted at blog.qrfs.com. If this article helped you learn about hydrostatic pumps, check us out at Facebook.com/QuickResponseFireSupply or on Twitter @QuickResponseFS.

Whether you are replacing an existing hose, or building a new system, you&#;ll need to select a hose of the correct pressure rating, diameter, and length and with the best material properties for your application. There are a few factors to consider carefully.

Material

Firstly, you should consider the conditions that a hose will operate under. The outer layer or cover of a hose can come in a variety of synthetic rubber materials. Some compositions can help with applications where abrasion may occur but may not bend as readily.

The most common materials are fluoropolymers and silicone, elastomers, metal, and thermoplastics. Composite or laminated materials are also common.

Rubber and elastomeric hydraulic hose are a strong choice when you need flexibility. A Fluoropolymer hose has a durable flex life, it also has excellent corrosion and chemical resistance and it can handle high temperatures.

Thermoplastic hydraulic hose has a tight minimum bend radius. It also features superior resistance to kinks. Thermoplastic hoses are generally much lighter than rubber hoses. The inner tube of copolyester or nylon is typically braided or spiral wrapped with a synthetic reinforcement fiber instead of steel. Synthetic fiber is also needed for electrically non-conductive (orange cover), aerial lift hoses. In many cases the outer cover of thermoplastic hoses will be polyurethane and provide a longer shelf life than rubber, better flexibility at low temperatures such as &#;60°C (&#;75°F), and higher resistance to UV and chemicals.

Metal hoses handle high temperatures and high flow materials well. They can also handle high pressures, as well as being either flexible or stiff.

Neoprene is one popular synthetic cover material that remains flexible across a wide range of temperatures, yet handles abrasion well. Most rubber hoses perform reasonably well from &#;40°C (&#;40°F) to 100°C (212°F).

Flexible hoses are easy to install and route compared to rigid tubing. The flexibility reduces noise and vibrations. It also dampens pressure surges and allows for movement between the parts.

Weight and Space

Another consideration when selecting a hose would be whether the weight and space are a concern, as is often the case with mobile machine. In this instance you would want to look for hoses with a thin-wall inner tube. Advances in synthetic rubber compounds allow for higher wall strength, allowing for a final product with a smaller outside diameter. Some manufacturers have moved to a reinforcement wire with an oval cross-section, as opposed to round, offering additional outside diameter (O.D.) and hose weight savings. These smaller O.D. hoses, referred to as compact models in many catalogues, also offer much tighter bend radiuses.

Inside diameter and Length

It&#;s very important to use a hose of the correct inside diameter. If the diameter is too small for a given rate of flow, the linear velocity will be too high and excessive velocity will translate into friction and turbulence, which when combined will surely result in noticeably higher system pressure and heat.

Correct hose length needs to allow for bending and flexing as a machine moves and articulates, and to make sure that no undue stress is caused at the crimped fittings. A hose that connects in a perfectly straight path from one component to another may shrink in length up to 4% at maximum pressure, so an allowance of extra length should be considered when making up the hose assembly. However, an excessively long hose adds restriction to flow, increasing system pressure and reducing system efficiency. A long hose length also requires a larger inner diameter to avoid excessive restriction and friction.

Pressure rating

A hose must be chosen with a maximum working pressure (WP) rating that is at or preferably above the normal maximum hydraulic system pressure. Momentary pressure surges for a hydraulic system are not to exceed this pressure rating. Hose fittings that are rated below the working pressure of the selected hose cause the entire hose assembly to be aligned to the lower rating of the fittings.

Burst pressure is a built-in safety factor for a hydraulic hose. A hose manufacturer verifies the burst pressure in a destructive test. The SAE standard J517 for the common series of 100R hydraulic hoses categorises leakage and also hose separation from hose fitting. The hose does not have to violently break apart completely to have suffered a burst failure. The burst pressure rating of a hydraulic hose if often 4x the working pressure rating or greater.

Price

When it comes to hydraulic design, hoses are not minor parts. Using economics as the only/primary hose selection criteria can easily leave human risks at a very high level. A hose burst failure is always a catastrophic incident. In the best case scenario, a hose failure might cause production downtime or environmental contamination concerns. In a worse scenario, persons could be seriously injured or even killed.

Hydraulic hoses comes in a myriad of design types and materials, and choosing the correct type for your application involves understanding several factors. You now have the rudimentary understanding needed to select the proper hydraulic hose for your needs. Remember that choosing the correct type and grade hose will extend its working life.

If you have more questions about hydraulic hoses, please contact us.

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