Sierra Series 830/840/860 Side-Trak™ and ... - Sierra Instruments
Sierra Series 830/840/860 Side-Trak™ and ... - Sierra Instruments
Sierra Series 830/840/860 Side-Trak™ and ... - Sierra Instruments
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Chapter 4 Maintenance<strong>Series</strong> <strong>830</strong>/<strong>840</strong>/<strong>860</strong> Instruction Manual<strong>840</strong> L, M <strong>and</strong> H seriesValve Adjustment ProcedureThe <strong>Sierra</strong> <strong>840</strong> L, M <strong>and</strong> H (low, medium or high-flow units) controlthe flow with a proportional electromagnetic valve that is setup for certain process conditions. Variables, which affect their operation,include orifice size, spring selection <strong>and</strong> adjustment, input<strong>and</strong> output pressures <strong>and</strong> gas-flow orientation (horizontal or vertical).If operating conditions change it may be necessary to make avalve spring adjustment. An adjustment may also become necessarydue to a valve-seat depression or spring sag, both of whichcan cause a change in the internal tension of the valve spring <strong>and</strong>electrical current. An incorrectly adjusted valve can be detected byOSCILLATION (UNSTABLE OUTPUT), NOT OBTAININGMAXIMUM FLOW, OR LEAKAGE AT A ZERO SETPOINT (LEAK-BY).The following valve adjustment procedure may correct the aboveconditions.Equipment needed:L <strong>and</strong> M:1/16” hex wrench5/16” nut driverH:St<strong>and</strong>ard screwdriver3/8” nut driver(Quick fix for leak-by). If your unit is experiencing leak-by, firstconfirm that this condition is mechanical in nature rather than electricalby shutting down the power. If leak-by stops (check fordownstream flow), the problem is electrical in nature <strong>and</strong> the instrumentmay require factory repair. If leak-by continues, theproblem is mechanical <strong>and</strong> may be fixed by an adjustment. Removethe small cover that is on top of the silver solenoid to theright of the rectangular electronic enclosure. (On some <strong>840</strong>L-unitsthis may require removing the plastic electronic enclosure to exposethe valve coil.) With the power off, apply the appropriate inletpressure to the controller per the inlet/outlet operating pressureslisted on your label <strong>and</strong> apply a zero setpoint. Loosen thelock nut. Adjust the center adjustment screw slowly clockwise(increasing the spring tension) 1/4 turn at a time until this leak-bysubsides. (Putting your finger over the outlet fitting can confirm4-12 IM-83/84/86-H
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