Tuesday 16 February 2016

What is the Balancing Valve function?

Balancing Valves. 
Balancing valves (Circuit Setters) are used to impose artificial head in all pipe routes besides the critical one to prevent short circuiting (excessive flow through lower pressure drop paths that results in insufficient flow through the highest pressure drop path). These valves are usually located on the return side (outlet) of the device as because this subjects their elastomers to lesser extremes of temperature and pressure, extending their lives. The most common type of balancing valve consists of a variable orifice and two pressure taps to measure the pressure differential across the valve. The flow rate is determined by measuring the pressure drop and noting the opening position of the variable orifice. Then a chart is used to find the flow rate.
Another type of balancing valve uses a flow sensor to measure the flow rate, plus some type of throttling valve, impeller trimming, or a variable speed drive to limit the maximum flow rate. This approach is generally more expensive, but has lower pressure drop and reduces pumping energy.
Automatic flow-limiting valves are preferred by some designers. They consist of a spring and variable orifice to limit the flow rate to the maximum intended for that flow path. They are commonly applied on heat pumps.
One apprehension with this type of control device is that there is often no way to measure flow other than to assume that the automatic flow limiting valve is operating properly. There is also no way to adjust the maximum flow rate without replacing the automatic balancing valve. The advantage is that no manual balancing is required if they operate properly and are not fouled by debris in the piping.

There is also a combined balancing valve which includes a shutoff valve.



There are 2 ports which are located on each side of the balancing valve for measuring the input and output flow rate for balancing.
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HVAC is the technology of indoor and vehicular environmental comfort. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. Refrigeration is sometimes added to the field's abbreviation as HVAC&R or HVACR, (heating,ventilating and air-conditioning & Refrigeration) or ventilating is dropped as in HACR (such as the designation of HACR-rated circuit breakers). HVAC is important in the design of medium to large industrial and office buildings such as skyscrapers, onboard vessels, and in marine environments such as aquariums, where safe and healthy building conditions are regulated with respect to temperature and humidity, using fresh air from outdoors. Ventilating or ventilation (the V in HVAC) is the process of "exchanging" or replacing air in any space to provide high indoor air quality which involves temperature control, oxygen replenishment, and removal of moisture, odors, smoke, heat, dust, airborne bacteria, and carbon dioxide. Ventilation removes unpleasant smells and excessive moisture, introduces outside air, keeps interior building air circulating, and prevents stagnation of the interior air. Ventilation includes both the exchange of air to the outside as well as circulation of air within the building. It is one of the most important factors for maintaining acceptable indoor air quality in buildings. Methods for ventilating a building may be divided into mechanical/forced and natural types.