VALVE OPERATION

TANK FILL OPERATION
(MODEL 8102)

A single sense line connects the pilot (mounted above the liquid level) to the ejector on the main valve. Through the ejector, inlet pressure on the valve is supplied to the valve’s upper control chamber (bonnet) and to the pilot valve. As the level changes the pilot responds by either discharging pressure off the bonnet of the main valve thereby allowing the valve to open (falling level), or diverting inlet pressure to the bonnet, causing it to close (rising level). Level is maintained.






TANK DISCHARGE OPERATION
(MODEL 8111)

The float pilot (mounted at the liquid level) is connected to the ejector on the main valve which is installed on the tank discharge line. Through the ejector, inlet pressure on the valve is supplied to the valve’s upper control chamber (bonnet) and to the pilot valve. In this application the float pilot is reverse acting. As the level changes the pilot responds by either discharging pressure off the bonnet of the main valve thereby allowing the valve to open (rising level), or diverting inlet pressure to the bonnet, causing it to close (falling level). Level is maintained.

It is important to note that this application requires the use of a pump between the tank and the valve. For gravity applications the configuration of the valve will change.

Note: In either tank fill or tank discharge, valve sizes up to 6” are controlled directly by the rotary float pilot as shown here. For valve sizes 8” and larger, the float pilot operates a Model 1356 relay pilot which, in turn, operates the main valve.







 HYDRAULIC REQUIREMENTS

For proper operation of bottom fill valves, and especially tank discharge valves, inlet pressure should be at least 5 psi greater than that of tank head. In brief, without the minimum 5 psi differential, the valve will not work. Lack of such minimum should not eliminate the valve from consideration. Refer to the Series 8100 Valve Selection Guide in this Tech Series for model numbers







 INSTALLATION

After the main valve is installed the pilot sense line must be connected to the float pilot. The proper installation of the pilot line is critical to the efficient operation of the float valve. Minimum recommended size for the sense line is 1/2” OD tubing or 3/8” pipe. The pilot supply port is 3/8” NPT.

In any float pilot installation where there is periodic or continuous turbulence within the tank, consideration must be given to shielding the float from such turbulence with a stilling well. Failure to do so can result in erratic valve control
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