RPZ valvehow it works

As an example, if you were connecting a potable water supply to the HVAC system, this would require backflow prevention because of the chemicals used in the HVAC system.

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An honest mistake that is commonly made is connecting fixtures that are used for personal hygiene downstream of the RPZ because it is in the same room. This results in a design that is not fit for purpose and it is also non-compliant.

CASE STUDIES Salon Republic, USA "The quality of the designs saw significant improvement with the adoption of h2x." "The software offers precision through detailed result outputs and advanced options for efficient pipe sizing, allowing heating engineers to optimise based on parameters like maximum velocity and pressure drop." Read the full case study

The strategic placement of heat pumps and careful sizing of pipework were crucial in maintaining minimal pressure drops over an 18-metre distance."

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Manufacturer’s usually have an easy to read graph that will enable you to quickly determine the correct RPZ valve size and the corresponding pressure loss. Note the RPZ does not always need to match the pipe size on the inlet to the RPZ.

This level of detail ensured that the heating load accurately matched each space's requirements, minimising energy waste and maximising comfort.

Regular maintenance is required for RPZ valves to ensure they operate correctly on an ongoing basis. With this in mind, it is important to design with the following considerations:

The sink requires the RPZ to prevent the chemicals entering the potable water supply. However, if you connect the basin downstream of the RPZ too, the design will allow chemicals to come out of the basin where someone expects it to be potable and could therefore potentially consume.

In the example below, there is a cleaners room that has a sink (used for mixing chemicals) and a basin (used for personal hygiene).

CASE STUDIES Greengate, UK "I would estimate over the length of this project, I have spent 50% less time designing than I would on our previous software. The ability to output the design straight into Revit assisted clash detection and coordination." Read the full case study

"The software offers precision through detailed result outputs and advanced options for efficient pipe sizing, allowing heating engineers to optimise based on parameters like maximum velocity and pressure drop."

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Series 800M4QT is designed to prevent back-siphonage of contaminated water into a potable water supply. The valve is ideally suitable for irrigation systems, industrial process water systems and other continuous pressure piping system applications where the water enters the equipment at or below its flood rim. The disc float and check valve are suitable for temperatures up to 140 degrees F. The resilient sealing float o-ring and seal check disc are silicone rubber which is resistant to heat, shock and chemical attack.

RPZ valvepool

As an example, if you were connecting a potable water supply to the HVAC system, this would require backflow prevention because of the chemicals used in the HVAC system. If the chemicals that are used in the HVAC system were able to enter the potable water supply, consumption of that water would pose a significant risk to public health.

A medical centre in Midwest U.S. saw the deaths of two patients who had unfortunately consumed water that was supposed to be potable (safe to drink). As there was no RPZ on the potable water supply to the HVAC holding tank where chemicals were mixed, when backflow occurred in the system, the chemicals made their way to the outlets of the basins and sinks throughout the medical centre.

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The image below shows how backflow can occur as a water main fails and also highlights the consequences when backflow prevention is not installed correctly. As shown, the water main fails and there is no backflow prevention installed to stop the toxic chemicals entering the ‘potable’ water supply to other buildings.

RPZ valveleaking

They discharge more than you expect and you need to have a sufficient drain below the RPZ valve to cater for it. In the example below, a 20mm RPZ with an incoming pressure of 483 kPa will discharge 2.4 l/sec.

"I would estimate over the length of this project, I have spent 50% less time designing than I would on our previous software.

Backflow is the reversal of the intended direction of water flow. This occurs when there is a significant drop in pressure in the upstream water supply which is commonly caused from water main failures.

CASE STUDIES Award-Winning Heating Design "Using h2x was pivotal, allowing for precise heat loss calculations, pipe sizing and flow rates for each room. This level of detail ensured that the heating load accurately matched each space's requirements, minimising energy waste and maximising comfort. The strategic placement of heat pumps and careful sizing of pipework were crucial in maintaining minimal pressure drops over an 18-metre distance." Read the full case study

As you can see in the example below, if you have a flow rate of 0.6 l/sec (25mm pipe at a 1.5 m/sec maximum velocity), you can use either a 20mm or 25mm RPZ valve and experience a similar amount of pressure loss.

Manufacturers will be able to provide you the relevant graph to determine how much water you can expect to discharge so that you can size the drain accordingly.