page 2
SERVICE ADJUSTMENTS
to safety timings and limits for ME995 (ME188) preset batch controllers.
INITIAL START (T2):
Once the START toggle is pressed, the controller allows a standard 1.5 seconds for pulses to arrive from the flowmeter. If
there are no pulses within the standard 1.5 second time period, the controller will shut down the output voltage drive, and turn on the Pulse Fail LED
and alarm warnings. In some applications, the 1.5 second delay may not be long enough, due to slow opening solenoids or slow pressure buildup
pumps etc. The initial start time period can be increased by soldering a tantalum capacitor in parallel with the standard capacitor value found on the
rear of the Printed Circuit Board (PCB). See Table 1 and diagram below, for values and location on the PCB.
FLOWRATE (T1):
If pulses do arrive within the allocated initial start time, the controller then locks the pulse-rate safety. Most ManuFlo Batch
Controllers have a standard 30 counts per second (30Hz) pulse-rate safety setting. If the pulses from the flowmeter drop below 30Hz, the controller
will shut down the output voltage drive, and turn on the Pulse Fail LED and alarm warnings. The 30Hz standard setting is typical with water
dispensing systems using RPFS-P paddlewheel flowmeters, where if the flowrate drops below 30 counts per second the pulse fail safety will
activate e.g. 50mm pipe diameter section (20 pulses/Litre), 30 Hz =1.5 Litres/sec minimum flowrate required. If flow drops below 1.5 Litres/sec, the
pulse-fail will activate. The equation is:
Pulse-fail frequency (Hz) = (Pulses/Litre) x (minimum flowrate of pipe diameter in Litres/sec)
The flowrate (frequency Hz) minimum setting can be adjusted by soldering a capacitor in parallel with the standard capacitor found on the PCB.
See Table 2 and diagram below, for values and location on the PCB.
Note: The flowrate safety timing is changed if required by very low flowrate applications, or when using flowmeters other than the most commonly
used RPFS-P paddlewheel pulse output flowmeters. (low pulse-rate/litre flowmeters). When controller/flowmeter systems are ordered, we supply
the safety timing setting to suit your chosen flowmeter, thus always providing the safest possible watchdog system.
LIMIT (LM):
The maximum permissible batch limit is determined by the factory-set internal limit value. The factory setting is always at the maximum
value. The limit setting can be reduced by simply de-soldering the limit lead wire (connected to the rear of rotary switch solder pads) and re-
soldering the wire to set the desired quantity (see diagram below).
Standard factory set values are T2: 1
μ
F capacitor, T1: 0.02
μ
F capacitor.
Use the following tables to change factory set values.
Table 1. INITIAL START TIMING (T2)
Table 2. FLOWRATE TIMING (T1)
Extra Capacitor value
Extra timing
Total Capacitor value
Frequency Hz (pulses per second)
1 µF
1.5 seconds
0.01 µF
30 Hz (RPFS-P)
2 µF
3.0 seconds
0.02 µF
25 Hz
3.3 µF
4.1 seconds
0.03 µF
20 Hz (low flowrate MES20)
4.7 µF
5.8 seconds
0.1 µF
07 Hz
0.2 µF
03 Hz
1.0 µF
0.2 Hz (PSM20-T flowmeters)
