Check the flow meter mechanical zero. Pointer should point to the zero reference mark on the dial with no flow. See Installation, Operation and Maintenance Manual (M1) page 4 for re-zeroing instructions.

 

 

Remove the back cover plate to gain access to the reed switches. Loosen the 2 adjustment clamp screws to the point where when moving the reed switches there is some resistance.

 

 

Connect a continuity tester to the common and the normally open or normally closed terminal on the terminal strip.

 

 

Move the pointer to the desired flow rate either by moving the lever or by establishing the desired flow rate through the flow meter (preferred method).

Caution: When moving the pointer using the lever method do not flex the lever forward or backward as this will distort the set point.

 

 

With the pointer at the desired set point, slide the reed switch until the tester changes state. The set point range window should indicate a partial or complete green mark. (When viewed from the rear, move the switch right for upscale and left for downscale.)

 

 

Check new set point by moving the lever or establishing flow to verify that switching occurs at the desired flow rate. Minor adjustments of the switch may be necessary to "fine tune" to the desired set point. Tighten the adjustment clamp screws taking care not to over tighten as over tightening may break the switch.

 

 

Replace the back cover plate adjustment to the reed switch set point is now complete. Click here for calibration video clip.

 

(See below for recommended reed switch electrical protection.)

1.

2.

3.

4.

5.

6.

7.

 

 

Page 1

Reed Switch Contact Protection

When switching inductive loads such as relays, solenoids and transformers, reed switch contacts require protection in order to ensure long, dependable life. When contacts open, the inductance or electrical inertia of the load generates a large high frequency voltage which appears across the switch contacts. If the voltage is large enough, it can arc, causing the contacts to burn, weld together or stick. The purpose of protecting the circuit is to prevent arcing by shorting this voltage through an alternate path.

 

Important:

• Don't be misled by the resistive rating of the switch. Most applications involve inductive loads.

• Don't be misled by the wattage rating of the load. Low wattage loads are often high inductive devices, making contact protection important.

D.C.

A 1N4004 diode (or equivalent) should be connected in series with the reed switch as shown in figure 1.

A.C.

Connect a resistor and capacitor in parallel with the switch.

Transient suppressors or varistors may also be used to dissipate the transient and protect the switch contacts.

Figure 1

DC Contact Protection

Figure 2

AC Contact Protection

Page 2

M6 Rev C Instruction Manual Reed Switch Option 1S2 / 2S2

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