Brooks Instrument 3750 - Manual (Page 35)

3-3
Installation and Operation Manual
X-VA-MT3750C-eng
Part Number: 541B063AAG
April, 2014
Brooks ® Ar-Mite TM MT3750C
Section 3 Operation
C.Two jumper configurations allow simultaneous use of both the high and
low alarm circuits. In the first of these configurations, an alarm is
always active. If the flow rate is under the set point, the low alarm circuit
is closed. If the flow exceeds the set point, the low alarm circuit opens
and the hi alarm circuit closes. There is hysteresis associated with reed
switches, so the flow rates at which the alarm switches between HI and
LO will be slightly different depending on whether the flow rate is
increasing or decreasing.
The second “Dual” alarm option allows separately adjusting the set
points for low flow alarm and high flow alarm within a limited range of
the maximum flow rate of the meter.
The dual setpoint alarm is set in the same manner as described in
Section 3-4. Simply use two ohmmeters to observe the behavior of both
circuits.
Table 3-1 Interior Label MT 3750 Ar-Mite Alarm.
Alarm Programming Table
Alarm Jumper Adjust Upper Lower
Flow Positions Sensor in Sensor
Range Region (2) Position
High, 60-100% J-2,5,7 B Bottom
of Slot
High, 40-75% J-1,4,6 A Bottom
of Slot
High, 0-40% J-1,3,5 B Bottom
of Slot
Low, 55-100% J-2,3,7 B Bottom
of Slot
Low, 40-75% J-1,4,6 A Bottom
of Slot
Low, 0-40% J-1,5,7 B Bottom
of Slot
Dual:
High, 40-75% J-1,4,6 A Bottom
Low, 30-60% of Slot
Dual:
High, 40-75% J-1,6,8 A Region B
Low, 10-45% (High Set) (Low Set)
(1) These ranges for reference only.
(2) Final sensor position may be slightly outside of these ranges.