Albion Valves: Take the pressure off water and energy

David Rhodes, Technical Manager of Albion Valves

David Rhodes, Technical Manager of Albion Valves, explains the urgent need to design for water efficiency – and highlights pressure reducing valves (PRVs) as part of a cost-effective technology to save this critical resource.

In Northern Europe’s hotter summers, droughts are a growing cause for concern. The UK uses around 14 billion litres of water per day, but the government estimates that this will rise to 18 billion litres by 2050. We must reduce that figure to prevent severe water shortages in the next decade.

The government published its Plan for Water in April 2023, outlining how it will tackle rising demand and the hazard of future droughts. It wants to reduce water use per head of population by 20% by 2030. This means cutting water usage in homes and other buildings.

Pressure reducing valves (PRVs) are an integral part of a system to ensure the effective distribution of pressurised water. Albion Valves have recently expanded their range of pressure reducing valves (PRVs) to include ½” to 12” (DN15 to DN300), and pressure ranges PN16, PN25, and PN40.

A 2022 UK government study into proposals for water efficiency labelling highlighted showers, toilets and kitchen and bathroom taps as significant water users in households and other buildings. PRVs can be applied to reduce water pressure, helping regulate water volumes and reducing water waste when outlets are in full flow. It may seem like a small step, but controlling water pressure this way can save significant amounts.

Take a tap outlet which is open for five minutes at 5 bar. It will pass around 15l to 20l per minute. However, if a PRV is applied to reduce the pressure to 3 bar, the volume of water from the tap drops to 12l to 15l over the same period, a saving of 25%. This works well in domestic settings, but if we extrapolate that to washroom sinks around a typical office building, it is easy to see why PRVs are invaluable for helping to reduce water waste.

Although they are simple in principle, PRVs must be specified correctly, based on flow and pressure, to make the most of their benefits. Therefore, avoiding selection of a PRV based solely on the line size is essential.

Correct sizing is vital to optimise performance and avoid damage to the valve. For example, a PRV which is too large will continually operate nearer to its ‘shut’ position, leading to erosion of the seat and eventual failure. On the other hand, if the valve is too small, then the volume of water rushing across the seat will cause unwanted noise, such as hammering.

There are two main types of PRV: direct acting and pilot operated. Both are designed using a pressure-loaded diaphragm, and selection depends on project requirements. For example, direct acting PRVs are best used for small loads. We see them widely applied on individual or small numbers of terminal units, such as apartments where taps, showers and baths are distributed throughout the property.

They generally have a compact size with a low price point and are simple to install. However, because of their size, they have a relatively low flow capacity and a higher proportional offset, or variation, from the set pressure.

Pilot operated PRVs are used for larger loads where close pressure control is required. They are often found in commercial or multi-residential properties, industrial buildings, and distribution systems.

This type of PRV can provide accurate control because the pilot valve is significantly smaller than the main valve, so it responds very quickly to minor variations in upstream load. With the addition of a trim to control the response time of the valve, the main valve has a lower proportional offset and therefore delivers a more constant downstream pressure.

Albion provides a range of PRV sizes and materials suitable for small domestic projects up to large commercial systems to ensure that contractors have everything they need for a successful installation.

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