Series
PF2A/PF2W
Specific Product Precautions 3
Be sure to read before handling.
1. Check regulators and flow adjustment valves
before introducing the fluid.
If pressure or flow rate beyond the specified range are applied
to the switch, the sensor unit may be damaged.
[For air]
2.
The fluids that the switch can measure
accurately are nitrogen and dry air. However,
only dry air can be measured with the high
flow rate type.
Please note that accuracy cannot be guaranteed when other
fluids are used.
3. Never use flammable fluids.
The flow velocity sensor heats up to approximately 150
°
C.
4.
Install a filter or mist separator on the
upstream side when there is a possibility of
condensate and foreign matter being mixed in
with the fluid.
The rectifying device built into the switch will be clogged up
and accurate measurement will no longer be possible.
[For water]
5.
The fluid that the switch can measure
accurately is water.
Please note that accuracy cannot be guaranteed when other
fluids are used.
6. Never use flammable fluids.
7. Install a filter on the inlet side when there is a
possibility of condensate and foreign matter
being mixed in with the fluid.
If foreign matter adheres to the switch’s vortex generator or
vortex detector, accurate measurement will no longer be
possible.
1. Since switch output remains OFF while a
message is displayed after the power is turned
on, start measurement after a value is
displayed.
2.
Perform settings after stopping control
systems.
When the switch’s initial setting and flow rate setting are
performed, output maintains the condition prior to the settings.
With the 100, 200, and 500
l
/min type switches for air, output
turns OFF when the switch’s initial setting and flow rate setting
are preformed.
3. Do not apply excessive rotational force to the
display unit.
The integrated type display unit can rotate 360
°
. Rotation is
controlled by the stopper; however, the stopper may be
damaged if the display unit is turned with excessive force.
[For air]
4. Be certain to turn on the power when the flow
rate is at zero.
Allow an interval of 10 minutes after turning on the power, as
there are some changes in the display.
5. Flow rate unit
Switch measures at mass flow rates without being influenced
by temperature and pressure. The switches use
l
/min as the
flow rate indicator unit, in which the volumetric flow is
substituted for mass flow at 0
°
C and 101.3 kPa. The
volumetric flow rate at 20
°
C, 101.3 kPa, and 65% RH (ANR)
can be displayed with the high flow rate type switches for air.
Others
Measured Fluid
Warning
Warning
Detection principle of digital flow switch for air
A heated thermistor is installed in the passage, and fluid absorbs heat from
the thermistor as it is introduced to the passage. The thermistor's resistance
value increases as it loses heat. Since the resistance value increase ratio
has a uniform relationship to the fluid velocity, the fluid velocity can be
detected by measuring the resistance value. To further compensate the fluid
and ambient temperature, the temperature sensor is also built into the switch
to allow stable measurement within the operating temperature range.
Fluid velocity
detection element
Temperature
compensation element
Detection principle of digital flow switch for water
When an elongated object (vortex generator) is placed in the flow,
reciprocal vortexes are generated on the downstream side. These vortexes
are stable under certain conditions, and their frequency is proportional to
the flow velocity, resulting the following formula.
f = k x v
f: Frequency of vortex v: Flow velocity k: Proportional constant
(determined by the vortex generator's dimensions and shape).
Therefore, the flow rate can be measured by detecting this frequency.
Fluid
Vortex generator
Vortex detector
This flow switch uses
l
/min
as the flow rate indicator
unit. The mass flow is
converted and displayed
under the conditions of 0
°
C
and 101.3 kPa.
The conversion conditions
can be switched to 20
°
C
and 101.3 kPa with high
flow type switches.
1.
Perform periodical inspections to ensure
proper operation of the switch.
Unexpected malfunctions may cause possible danger.
2. Take precautions when using the switch for an
interlock circuit.
When a pressure switch is used for an interlock circuit, devise
a multiple interlock system to prevent trouble or
malfunctioning, verify the operation of the switch and interlock
function on a regular basis.
3. Do not disassemble or perform any conversion
work on flow switches.
Maintenance
Warning
Measured Fluid
Warning
∗
Top view
16-11-34
