Model 8670 SUREFLOW Room Pressure Controller Manual - TSI

WARNING: The low and high alarms must be set in the same direction as the setpoint. The
SUREFLOW does not allow a positive setpoint and a negative low alarm.
Constraints There are a number of constraints that prohibit the user from incorrectly adjusting the
setpoints. These are as follows:
1. The magnitude of the LOW ALARM setpoint must be set at least 20 ft/min
below the control SETPOINT (see Appendix C for relationship between
pressure and velocity). The SUREFLOW will not allow the LOW ALARM
setpoint to be set any closer. For example, if the control SETPOINT is set at
-100 ft/min, the highest the LOW ALARM setpoint can be is -80 ft/min. This
is done to prevent nuisance alarms from occurring during natural fluctuations
of the system.
2. The magnitude of the HIGH ALARM setpoint must be at set at least 20 ft/min
above the control SETPOINT. The SUREFLOW will not allow the HIGH
ALARM setpoint to be set any closer. For example, if your control
SETPOINT is set at -100 ft/min, the lowest the HIGH ALARM setpoint can
be is -120 ft/min. This is done to prevent nuisance alarms from occurring
during natural fluctuations of the system.
3. The alarm setpoints automatically follow the same alarm offsets when the
SUREFLOW is placed in the REMOTE SETP mode. Consider a unit set up as
follows:
LOW ALARM SETPOINT HIGH ALARM
-60 FT/MIN -100 FT/MIN -150 FT/MIN
(-.00030 "H2O) (-.00085 "H2O) (-.00200 "H2O)
When this unit is placed in the REMOTE SETP mode where the REMOTE
SETP is set to 80 ft/min, the following conditions will be employed:
REMOTE SETP REMOTE SETP REMOTE SETP
LOW ALARM SETPOINT HIGH ALARM
+40 FT/MIN +80 FT/MIN +130 FT/MIN
(+.00010 "H2O) (+.00055 "H2O) (+.00150 "H2O)
Notice the 40 ft/min difference between the LOW ALARM and SETPOINT
was maintained in both the normal and setback modes of operation. Similarly,
the 50 ft/min difference between the SETPOINT and the HIGH ALARM was
also maintained in both modes.
Setpoints Menu 23
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