What you should know about valves

Steps to Identify the Right Valve for a Data Centre

To find a valve that meets your criteria and is the most efficient choice, it's helpful to adopt a methodical strategy. By following these step-by-step guidelines, you will be able to identify valves that are compatible with your project requirements. This is demonstrated through the example of a cooling circuit designed to supply a heat exchanger in a data centre. The specified volume flow rate in this scenario is 200 m³/h, resulting in the recommended nominal size of DN 150.

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1. What Function Needs to Be Fulfilled?

The valve is required for a shut-off purpose (OPEN/CLOSED). Other functions include measuring, throttling, or control.

Suitable Valves:

Gate valve / globe valve / ball valve / butterfly valve / diaphragm valve

2. What Fluid Will Flow Through the Valve?

Consider the chemical properties of the fluid. Is it corrosive or abrasive? Does it contain solids or have the potential to be explosive? The material of the valve must resist the fluid being handled. In this example, the fluid is cooling water employed in a closed circuit.

Suitable Valves:

Gate valve / globe valve / ball valve / butterfly valve / diaphragm valve

3. What Are the Temperature Requirements?

Both fluid temperature and ambient temperature are crucial when selecting an appropriate valve. Key temperature limits generally include ranges from -50°C to +350°C, necessitating different materials at these extremes. In this case, the fluid temperature is +6°C, and the ambient temperature is +20°C, indicating an indoor environment.

Suitable Valves:

Gate valve / globe valve / ball valve / butterfly valve / diaphragm valve

4. What Are the Pressure Requirements?

Consider the pressure the valve must maintain against the ambient atmosphere. What is the pressure or differential pressure that must be regulated between the inlet and outlet? In this instance, the system pressure is approximately 8 bar, with a planned nominal pressure class of PN 16.

Suitable Valves:

Gate valve / globe valve / ball valve / butterfly valve / diaphragm valve

5. What Standards, Regulations, and Acceptance Criteria Are Needed?

In this example, the valve must comply with the safety requirements outlined in Annex I of the European Pressure Equipment Directive /68/EU (PED) for Group 1 and 2 fluids. Furthermore, maintenance-free operation is desired.

Suitable Valves:

Gate valve / globe valve / ball valve / butterfly valve / diaphragm valve

6. Resistance Coefficient ζ, zeta

Since efficiency is paramount for our system, we are in search of a valve with an exceedingly low resistance coefficient, which eliminates one valve type from our consideration.

Suitable Valves:

Gate valve / globe valve / ball valve / butterfly valve / diaphragm valve

7. How Much Space Is Available for the Valve?

Space is quite limited. A more compact valve design is preferable, particularly for a 1:1 replacement of existing valves, thus excluding two other options.

Suitable Valves:

Gate valve / globe valve / ball valve / butterfly valve / diaphragm valve

8. What Is The Free Passage Required?

This is relevant to pigging and whether solids will pass through the valve. In this case, it is not applicable.

Suitable Valves:

Gate valve / globe valve / ball valve / butterfly valve / diaphragm valve

9. Are There Any Hygienic Requirements for the Valve?

This is crucial, particularly in drinking water installations and the food industry, but our example has no such requirements.

Suitable Valves:

Gate valve / globe valve / ball valve / butterfly valve / diaphragm valve

10. The Price/Performance Ratio

Budget constraints and the desired security from investors dictate the need for cost-efficiency while still fulfilling requirements. Availability and interchangeability are also key considerations. For instance, a ball valve in DN 32 or DN 50 would be cheaper than a butterfly valve requiring a flanged connection; however, the latter is unsuitable for the 200 m³/h flow rate in our example. The required valve must meet the DN 150 specifications, ruling out the final option.

Suitable Valves:

Gate valve / globe valve / ball valve / butterfly valve / diaphragm valve

Conclusion:

The methodical approach has successfully led us to our ideal valve for this project: a butterfly valve.