Table of Contents
How do you calculate valve authority?
Mathematically it is easy to see how, as the authority of a control valve is defined as: N = DPv / (DPv + DPc). Where: DPv = Pressure drop across a fully open control valve DPc = Pressure drop across the remainder of the circuit.
How is Cv calculated in control valve?
Inlet Pressure 32 kgf / cm2 Convert to absolute pressure = 33.03 kgf / cm2 (A). Outlet Pressure 15 kgf / cm2 convert to absolute pressure = 16.03 kgf / cm2 (A). Because the fluid is a gas and ΔP ≥ P1 / 2 so we will use the formula. Cv = (48000 / (248 × 33.03)) x sqrt (0.86 x (273 240)).
What is good valve authority?
It is generally considered that: 0 – 25% Valve authority provides unstable to fair control with a low pressure drop. 25 -50% Valve authority provides fair to good control with reasonable pressure drop. 50%-100% Valve authority provides good to excellent control but with a high pressure drop.
What is meant by valve authority?
Valve authority is the definition of how well a modulating control valve will control flow under the influence of other elements in the HVAC system.
What is valve capacity?
Valve Flow Coefficient (Cv) is a valve’s capacity for a liquid or gas to flow through it. It is technically defined as “the volume of water at 60°F (in US gallons) that will flow through a valve per minute with a pressure drop of 1 psi across the valve.”
What is KVS value of valve?
The Kvs value expresses the amount of flow in a regulating valve at a fully-open valve position and a pressure differential of 1 bar. The Kvs value is a special case of the Kv value, which indicates the flow at a given valve position and a pressure differential of 1 bar.
What is valve authority?
Valve authority is a term used to describe the basis on which a Control Valve is selected. The term describes the correlation between the Control Valve resistance and the remaining circuit resistance.
What is control valve sizing?
The process of “control valve sizing” is a procedure where the dynamics of the system are matched to the performance characteristics of the valve. This produces a control valve of an appropriate size and type that will best meet the needs of managing flow within the process system.
What is Cv and KVS?
The Valve Coefficient (Cv – in Imperial unit) – the number of US GALLON PER MINUTE of water at 60 °F that will flow through a valve at specific opening with a pressure drop of 1 psi across the valve. The flow factor (Kv – in Metric unit) – the amount of water that will flow in m3/hr.
How do you calculate the authority of a control valve?
To calculate the authority, the pressure drop across the Control Valve in fully open position has to be considered, as the pressure drop across the valve is at its minimum in the fully open position. This value is represented as (ΔPv).
Are valve authority calculations relevant in variable flow systems with picvs?
However, in a variable flow system with PICVs valve authority calculations are relevant when sizing 3-Port and 4-Port Valves, for say, end of line Control Valves to provide terminal unit control plus dead leg and low flow pump protection.
Valve Authority The valve authority expresses the ratio between pressure drop across the control valve compared to total pressure drop across the whole system
How does a PCV valve work on a V8?
With a PCV valve gases are fed back into the intake manifold as part of a fresh charge of air and fuel. This is accomplished by drawing in a clean source of fresh air via a breather. On a V-8 the typical fresh air source is the opposite valve cover from the PCV valve.