EME/

H/V

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HVAC Product Catalogue page 46

Auto Flow Control Valves

General Design & Application

Econ Automatic flow control valves (flow limiter) are designed to maintain (limit) a preset specified flow rate with in a specified pressure differential ( p) range. The flow shall be varying above and below the specified p range across the AFCV.

The AFCV is equipped with a flow rate cartridge which has a SS 316 cylinder where orifice areas (through which the liquid flows) are cut and is fixed to a POM body along with the SS spring. The basic flow equation can be simplified as: Q = A x p, where Q = Flow rate A = Area

p = Differential pressure

The cartridge is designed to change the orifice area in order to maintain the constant flow when changes in p occurs across it due to various reasons (with in the specified p range). Below and above the p range, the cartridge acts as a fixed orifice and the flow will vary as per the differentialpressure available. According to the below figure, we can see that the flow is maintained with in the p range. These valves will automatically balance the entire circuit, irrespective of constant flow or a variable flowsystem.

Selection

Q

p range determines the range of minimum and maximum differential pressure the valve will

experience during the course of operation in the sub circuit where it is installed. Select the cartridge p range from the flow chart given, which will accommodate both these minimum and maximum values. Flow rate : The flow rate is selected close to the design flow rate from the various flow rates shown in the above selected p range from the flow chart.

EME/

H/V

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HVAC Product Catalogue page 48

DRV System Risers and Branches

AFCV System Risers and Branches

DRVDRVDRV

DRV

DRV

DRV

DRV

DRV

DRV

IV

IV

IV

IV

IV

IV

IV IVIV

Typical Coil connection - Schematic

IV

PG TH

M C V

FCSTR

FC

PG TH

AFC V

IV

Cooling / Heating Coil