How to choose the right valves

1. Open/close or change-over of product streams
   The simplest open/close valves are the DELTA SV/SVS butterfly valves which can be operated manually or automatically. The modest installation dimensions of these valves make them well suited for process plants with confined space. The DELTA SV/SVS valves consist of a few simple parts, making them an economic choice in terms of both the initial purchase and any later maintenance. An alternative to the butterfly valve is the DELTA SW4, DELTA S2 and VPM range of single-seat valves, which comes in manually and automatically operated versions. Apart from being available as open/close valves, they can also be offered as change-over valves with a wide variety of housing configurations.
   
   A common characteristic of the above valves is that the stem moves in and out of the valve. This means a minor risk of bacteria getting into the valve from the outside. In order to eliminate this complete, the DELTA M4 and DELTA MP4 have been developed. These valves are equipped with a membrane that ensures strict separation between the inside and outside of the valve.
   
   
2. Safe separation of incompatible media
   In an application where it is of the utmost importance that two incompatible media are not mixed, more than one valve seat is required. The DELTA SD4 and DELTA SDM4 have two valve seats, corresponding to a valve stem with two seals. Product mixing is thus avoided even if one of the seals breaks.
   
   The ultimate mix-proof solution, which separates the two media by means of two independent valve stems, each with its own valve seats, is called the DELTA DE3 and DELTA DA3+ range.
   
   Finally, you can choose a double-seat ball valve called the DELTA DKR or DELTA DKRT in a tank outlet version. These valves have spherical discs, so when the valve is in the open position, a full bore will be achieved, i.e. no stem or disc to disturb the flow and no pressure losses over the valve.
   
   
3. Protection against excessive pressure and pressure shortage
   When the issue is to protect the plant against extreme pressures, protection valves are the solution. Depending on the situation, various options are on hand.
   
   The DELTA SI2 is a safety valve used to protect the tank against over-pressure.
   
   If you need protection against a vacuum, you should choose the DELTA VRA ot the DELTA VRAH.
   
   If it is extremely important to make sure that the flow from a pump can run freely, as high pressures will otherwise build up, a pressure relief valve, the DELTA UF, is recommended.
   
   In some cases, it is essential to ensure that the media does not run backwards in the pipeline. This might happen if the pump stops. To handle this, the non-return valves DELTA RUF and VPN are available.
   
   
4. Sampling of products from the pipeline
   When bacteriologically safe samples from the process line are needed, the valves to select are the DELTA PR2 and DELTA PRD2.
   
   
5. Flow and pressure regulation
   When the application requires a valve that is neither open nor closed, but can be set to any position in between, the DELTA RG4 or RGE4 valves should be selected. The valve stroke is coordinated with the setting signal, independently of the product pressure and throughput or any disturbances. Both linear and equal percentage characteristics are available.
   
   

6. Control units for valves
   Valves are available with the new generation of control units, the DELTA CU and DELTA CU Valve-Net. The DELTA CU is designed for multi-voltage operation. It has a built-in solenoid valve and hall proximity switches.
   
   The DELTA CU Valve-Net has the same features, but it communicates with the PLC by means of a fieldbus system.