2Double Check ValveBackflow Preventer

The Double-Check Assembly (Figure 1) was developed in the 1950s for the fire industry. Any time the pressure on the property (downstream) side exceeds the pressure on the city (public) side, the two redundant check valves close stopping the backwards water flow. There are two problems with the Double-Check backflow preventer. First, no remedy exists in the event of a malfunction of the valve closures or if debris in the water line causes the valves to not close completely. Second, and this is the big problem, there is no way to know when such a failure has occurred without conducting a full test by a qualified professional.  The Double-Check is a closed system. It has no method of revealing whether the internal check valves are functioning properly and no way to detect the presence of debris that is impeding full closure.

Double Check Valveprice

Changing Water Pressure: You may notice that as you take a shower or do your dishes there will initially be high water pressure, but then it drops off starkly.

Powers™ HydroGuard® 6550026 LFLM490-10 Thermostatic Tempering Valve, 1 in Nominal, C Union End Style, 125 psi Pressure, 23 gpm Flow Rate, Brass Body, ...

double check valve3/4

The Truckload Carriers Association is the only trade association whose focus is the truckload segment of the motor carrier industry. We're #TruckloadStrong!

WATTS LFUSG-B-M2 0204143 3/8 THRD BRASS THERMOSTATIC MIXING VALVE LEAD FREE at Plumbing, Industrial, & HVAC Supply Richmond, VA.

You’ve heard these phrases and acronyms repeatedly. If you are a designer, you feel sure that you are expected to know what they mean. Here’s a quick rundown on what they are and how they differ.

A designer may specify one of 2 types of backflow prevention devices. First, the Double-Check Valve Assembly. This is often shortened to DC and is typically thought of as the appropriate solution for low hazard conditions. Second, the Reduced Pressure Zone Valve Assembly, often shortened to RP or RPZ, is thought of as the appropriate solution for high hazard conditions.

PRVs are located near the shutoff valve on your main water supply line where the water enters your house. A PRV’s main job is to keep the water pressure stable, even when water events change the pressure. For example, fire fighting trucks use a ton of water to fight fires. Because of this, it can affect the water supply levels and sometimes disturb the existing water supply. A pressure reducing valve prevents the water from flowing backwards into your home’s water.

When a flow stop occurs, both check valves close. At that moment, the relief valve opens and evacuates the water between the valves. (Figure 3) Some think that this event defines the limit of how much water can ever flow from the RPZ into a drain. This is not so.

Double Check Valvediagram

Hammering Pipes: If your pipes are extremely noisy and make hammering sounds while your water is on, the water pressure is too high for your infrastructure to handle.

How do you determine hazard? The simple answer is that the purveyor determines it, but every jurisdiction is different. Every city has its own list of named examples for what constitutes the hazard threshold. Here is an example from Washington DC. They also stipulate that if the anticipated use, as you know it, is not named explicitly, then they reserve the right to make the decision during plans review. It’s also important to understand that you cannot, as a designer, over-protect the incoming water service. This means there is no penalty for providing the higher degree of protection.

The easiest way to determine if your Pressure Reducing Valve is working correctly would be to locate the arrow on the valve. This arrow indicates the direction of the water flow. This arrow should be pointing from the meter to your home or commercial property.

Media-Assisted Crystallization Cartridge for OneFlow Plus System, OFPSYS.

Double check valvesymbol

A ball valve is a shut-off valve that controls the flow of a liquid or gas by means of a rotary ball having a bore.

Now consider a full failure of the #2 check valve, like one that might occur if the device is knocked out of round or has a mechanical failure. It’s essentially the same event with the exception that due to the larger valve opening, there is actually a higher flood rate. Now you have water flowing through the relief valve at full head pressure. Again, if this is a large or multi-story building, that’s a lot of water very fast.

The main thing to take away from this is that both backflow prevention device types perform the same function when they are operating properly, but only the RPZ is designed to protect the public water supply by disposing of any backwards-flowing water if any of the check valves or the relief valve fails.

Double Check ValveAssembly

double check valve1/2

Consider a flow-stop situation, like one that might naturally occur at the end of the day (Figure 4). If you look closely, you can see that a small pebble has lodged in the #2 check valve. Now imagine some sort of back siphon event over night. Perhaps a nearby building fire leaches the water back with the draw of a fire hydrant; or a pump station fails; or a water main breaks. Because the #2 check valve is not closing, all the water that has been delivered to the building will continue to flow out the relief valve until the private lines are cleared. If this is a four story building, that’s a lot of water.

Another component to check is the material of your PRV. Instead, ensure your valve is made fully of brass. Many home builders use lower-quality valves; PRVs with plastic caps will often not even last a year. Finally, the reason many PRVs fail is that they are located in the ground which can be very corrosive.

The Reduced Pressure Zone Valve Assembly (Figure 2) consists of two independently operating check valves just like the Double-Check as well as a hydraulically operated differential relief valve located below the first check valve.

Unfortunately, the city can increase your water pressure at any time to accommodate new construction. In fact, having a PRV has been mandatory for all homes in Austin with a PSI of 80 since 1980; however, each jurisdiction can override that regulation if they choose to. Homeowners in Austin can take advantage of a PRV rebate, provided by the City of Austin.

The Shurflo water pressure reducer valves are designed to stabilize incoming water pressure fluctuations and guard against sudden pressure spikes.

Order Powers Intellistation 1"Jr DgtlWater Mxng Valve, LFIS100 at Zoro.com. Great prices & free shipping on orders over $50 when you sign in or sign up for ...

Then as water is drawn out, the mixing valve mixes cold water with that very hot water to deliver whatever temperature the homeowner chooses as their set point, ...

Watch the video below for an example of RPZ flooding and to see just how much water is discharged when a small amount of debris becomes lodged in the device.

Bolt Issues: If you adjust the pressure using your Pressure Reducing Valve and the bolt on the valve breaks, it’s time to replace it.

23 Sept 2024 — A pressure reducing valve will cost between $300-400 in Victoria to supply and install by a licensed plumber (the plumber must hold a VBA ...

If you’re in the Austin or San Antonio areas, choose Reliant Plumbing for all of your Pressure Reducing Valve needs. Give us a call today!

Double check valveAir brakes

You should always replace your PRV when you notice any of the above issues, but depending on the quality of your valve, you may want to replace it every three to six years. The best PRV’s are made of solid brass, no plastic parts. Keep in mind that you won’t want to replace your valve within its first year of being installed due to a risk for corrosion.

Have a question about a backflow preventer enclosure?Click the contact us button below and one of our experts will be able to help with your specific enclosure needs.

Pressure Reducing Valves, abbreviated as PRV, are valves that decrease incoming water pressure into your home. Although high water pressure is often seen as a positive, most homes should have a maximum PSI of 75. Anything above 75 can be detrimental to your comfort and home. Normal operating pressure is 60-65. This level of water pressure is more comfortable and better suited for your home’s infrastructure. Because of this, many homeowners choose to add PRVs to their homes for the health of their fixtures such as water heaters and RO systems.

Besides improving the comfort level of your water when your water pressure is too high, PRVs have a few additional benefits. Adding a PRV can reduce water waste and improve energy savings. Most of our clients experience savings on their utility bill when less water is rushing through the pipes for the same effect. In fact, our plumbers agree that high water pressure is the leading cause of slab leaks, broken fixtures (as many can only manage certain pressure levels), leaky faucets, broken pipes, water heaters, and water softeners. Just like blood pressure in your veins, high water pressure can weaken your pipes ability to hold the water.

This hydraulic valve and its placement makes the RPZ virtually fail-safe but it comes at a cost to the area around the device.

2013327 — A.2 Install balancing or throttling valves (shutoff valves) in hot
. and cold legs to hot water extender tempering valve and
.