RPZ calibration tests should be done annually by accredited contractors and plumbers. While most companies only undertake calibration tests on the gauge on an RPZ tester, it is a good idea to test the system for leaks, inspect wear and tear of the valves, and account for pressure differences if any. Testing the entire RPZ assembly allows early detection of malfunction within the parts of the RPZ unit.

Unless the valve is specifically approved for vertical installations, RPZ valves should be installed horizontally with the relief valve mechanism discharging downward. In order to prevent any fouling of the RPZ assembly elements, plumbing engineers should install in-line strainers upstream of the RPZ valve. The valves must be installed above the floor surface to facilitate easy and fast inspection, testing, and maintenance.

Rapid and unexpected reduction of pressure in pipelines can present an extreme risk of contamination to water supplies. When water pressure goes down, water flows in the wrong direction, bringing contaminated water from home appliances and other industrial processes with it. Even the slightest fluctuation in pressure can cause backflows and contaminations.

The Department of Health made it mandatory that all water systems that provide water for nonpotable use should use backflow preventer systems such as the RPZ. This means that public water supplies, commercial property owners, and residential property owners should install backflow systems to protect users from health hazards that can result from water contamination.

RPZ valves are pivotal in preventing toxic chemicals, hard metals, pesticides, and other harmful compounds from contaminating water supplies. In residential buildings, a RPZ device is used with sprinkler irrigation systems, boiler systems, fire suppression systems, and forced-air furnaces where it acts as a safety mechanism.

When installing RPZ valves, contractors should avoid installing them in areas prone to flooding, places above electrical equipment, and positions that expose the valves to mechanical damage. The area should also be in a heated enclosure to prevent freezing, which can lead to ice buildup inside the valves, which can block water from flowing.

Fig. 3 Delivered steam pressure is regulated in a similar manner as direct acting PRVs, however indirectly via a pilot valve. As the pilot valve is actuated, it provides the opening flow to the larger main valve which can supply significantly higher flow rates than the pilot itself. The pilot valve is then equalized by the secondary pressure, which correspondingly controls the opening flow to the main valve.

Reduced pressure zone assemblies, also commonly referred to as reduced pressure zone (RPZ) valves or RPZ backflow preventers, are an essential system that prevents the backflow of clean water to avoid contamination.

Because of fluctuating pressures, designs should factor in the intensity and frequency of the fluctuations. For instance, installation of a single-check valve upstream of the RPZ valve prevents fluctuation of pressures upstream, which are usually the primary cause of frequent discharges through the relief valve.

While it is possible to maintain a constant pressure by using the combination of an actuated control valve, a pressure sensor, and a controller, a pressure reducing valve offers the advantage of being able to control pressure through fully-automatic self-contained operation, requiring no type of external power source. It can offer the further advantage of extremely rapid response action by immediately sensing and adjusting based on the downstream pressure.

In direct acting pressure reducing valves, the amount of valve opening is determined directly by the movement of the adjustment spring. If the spring is compressed, it creates an opening force on the valve which increases flow. As pressure builds downstream, equalizing occurs by feeding the downstream pressure to the underside of the adjustment spring (usually against a bellows or diaphragm) where its upward force counter-balances against the spring compression. Spring compressive force which opens the valve is limited to allow sufficient spring sensitivity to equalize with downstream pressure changes. The net result is simple pressure control through a valve orifice where high flow rates can cause pressure droop.

RPZ backflow preventers must be set up in areas with adequate drainage because a large volume of water will flow from the relief valve. For this reason, RPZ assemblies shouldn’t be installed in areas where the discharge water can cause damage — adequate drainage must be considered in areas fitted with RPZ valves.

In a typical RPZ assembly, two one-way valves are connected to prevent water from returning to the supply line. This system works by ensuring that the incoming fluid has a higher pressure than the water entering the downstream supply. To prevent minor backflow leakage, the closure of one valve creates a pressure differential, thus tightening the valves and effectively sealing the system from backflow.

Whether you are a municipality or a property owner, complying with Illinois’ backflow protection codes means installing a robust backflow prevention system. Thankfully the team of experts at Dahme Mechanical Industries is fully certified and able to perform RPZ backflow prevention installation, testing, calibration and repair. We serve Arlington Heights and the surrounding communities, including Schaumburg, Des Plaines, Palatine, and more. Contact us today to learn more!

Also, use of pesticides or fertilizers in your backyard together with your home’s fire suppression system poses a danger. The standing water in your water supply system can get trapped and lead to bacterial and mineral growth, which can contaminate your clean water supplies.

From the above characteristics, it can be seen that the function and applications of non-piloted direct acting PRVs differ substantially from those of pilot-operated PRVs.

A common way of lowering pressure is by throttling down the size of the steam passageway. For the most basic pressure reduction, it is possible to simply use a conventional globe valve in a fixed partly-open position, or by inserting an orifice plate into the flow of steam. However, any fluctuation in flow rate would be accompanied by a corresponding fluctuation in pressure. To avoid such circumstances, pressure reducing valves (PRVs) can be used to provide precise control of downstream pressure. They automatically adjust the amount of valve opening to allow the pressure to remain unchanged even when the flow rate fluctuates.

The three-valve RPZ and the five-valve RPZ are the common RPZ testers approved for testing backflow systems. Since the five-valve RPZ tester allows testing procedures to take place without disconnecting any hoses, it is the most popular tester.

Only a certified assembly tester should perform the RPZ backflow preventer test, using a properly calibrated tool. Testing procedures may vary from state to state, but it must comply with the Department of Health and Illinois Plumbing Codes. Building maintenance workers, contractors, and plumbers use RPZ testers to measure the pressure difference between two points.

In pilot-operated pressure reducing valves, a pilot valve is used to load a piston or diaphragm that increases the downward force used to open a larger main valve. This enables larger flow capacity with a lower pressure offset (droop). The opening and closing of the pilot valve is controlled by the balance of force between the adjustment spring and the secondary pressure in the same manner that a direct-acting valve operates. However, in a pilot-operated PRV, this opening and closing of the pilot valve purposely delivers pressure to the main valve piston or diaphragm. This pilot flow pressure then causes a downward force that is amplified by the area of the piston or diaphragm to enable opening of a much larger main valve, which in turn provides the ability for very high flow rates.

RPZ backflow preventers are designed to prevent contaminated water from mixing into clean municipal water supplies and are commonly used by municipalities, homes, and commercial buildings. These valves provide reliable protection against back pressure and siphonage, safeguarding water supplies from any form of contamination.

For a municipal water system, if at any time the pressure at homes exceeds the pressure on the supply side, the two RPZ valves close preventing backflow. If either of the check valves leaks, the relief valve is designed to open and discharge water to the outside, ensuring that water never returns to the supply line.

When there is a water leak in your supply lines, hydrant flushing, city water main break, or use of hydrant to fight fire, pressure in the water system drops. When this occurs, a RPZ prevents backflows, effectively preventing clean water from backing up to supply systems hosting potential contaminants.

In a steam-using plant, steam is often generated at high pressures and reduced locally to provide heat for each steam user. This is usually done to minimize the diameter of steam distribution piping and enable more cost-efficient steam delivery.

Because the downward force is amplified through the use of a piston or diaphragm, a small change in the opening on the pilot valve can result in a large change in flow and downstream pressure through the main valve. As a result, there is little change needed in adjustment spring force on the pilot to accomplish quick response over a wide range of steam flow rates. Quick response and tight delivered pressure control represent the main advantages of this type of valve over the direct-acting type.

Fig. 2 Delivered steam pressure is regulated by balancing forces acting directly on the valve itself: the downward force caused by compression of the adjustment spring against the upward force from the secondary pressure acting against the underside of a bellows or diaphragm.

After the installation process, the reduced pressure zone device installed on plumbing systems requires regular tests by certified plumbers. Illinois water protection codes state that RPZ valves must be tested at least once every year. These tests are essential as they ensure that the valves are operating efficiently to protect the city water supply and drinking water from contaminants.

Calculate and display steam property values using pressure-based saturated steam tables, temperature-based saturated steam tables, and heating steam tables.

Because of their design, RPZ backflow preventers experience more high volume and pressure loss than double-check systems. Plumbers must account for these losses when designing drainage systems. Fluctuations of pressure, either downstream or upstream, will prompt the RPZ assembly to discharge small amounts of water periodically.

In pressure reducing valves, the mechanism that automatically adjusts the downstream pressure typically uses the balance of forces between the steam pressure and an adjustment spring. At present, this is a universal concept on almost all manufactured pressure reducing valves. However, there are two different ways in which this mechanism is implemented to control the amount of valve opening: