INSTALLING AND OPERATING THE KELCO F21 SERIES FLOW SWITCH
INTRODUCTION
This F21 flow switch may have been supplied in one of several available configurations. The model number of the specific switch is located inside the lid of the electrical housing. The
F21 series flow switch is a versatile heavy-duty paddle flow switch suitable for detecting flow of liquids in pipes of any diameter from 25 mm (1”) upward. This flow switch has several
unique features:
A)
The complete electrical assembly can be removed from the switch by undoing and removing the locking screw in the split clamp on the side of the switch’s electrical
housing. With the locking screw removed, the electrical housing can be pulled straight off the wet end of the switch. Removing the electrical housing allows the wet end of the switch
to be unscrewed from pipework without disturbing the cable connection to the switch. This means the paddle of the switch can be changed, inspected or trimmed without the need to
disturb the electrical connection to the switch. replace and tighten the locking screw after completing any work on the wet end of the switch.
B)
The standard version of the F21 flow
switch has a built-in manual override. On the end of the switch body underneath the cable entry port is a spring loaded push button. Pressing this button actuates the switch, regardless
of the state of flow. Pumping systems can be manually started by pressing this button and holding it in until flow is established. The override button can be used to test control circuits
and wiring during commissioning, without the need for water in the pipework. The button is spring loaded so it can’t be inadvertently left in the on position and only overrides the flow
switch while it is pressed.
Warning note on operating limitations:
Maximum operating pressure of the Polypropylene F21-S must be linearly de-rated as operating temperature is increased so that at 60°C
the maximum permissible operating pressure for the switch is not more than one Bar Absolute.
INSTALLATION
OPERATING LIMITATIONS
ELECTRICAL DATA MICROSWITCH MODELS
Model
F21-S
(All Poly)
F21-SS
(Stainless)
F21-D
(Diesel)
Maximum operating pressure
(Static or Dynamic) at ambient
temperature
18 Bars
(261 PSI)
200 Bars
(2900 PSI)
200 Bars
(2900 PSI)
Minimum burst pressure at
ambient temperature
45 Bars
(652 PSI)
500 Bars
(7251 PSI)
500 Bars
(7251 PSI)
Maximum operating
temperature
60ºC
See note
below
80ºC
80ºC
Minimum operating
temperature
0ºC
0ºC
0ºC
Minimum liquid S.G.
0.8
0.8
0.8
RATED
VOLTAGE
NON INDUCTIVE LOADS
INDUCTIVE LOADS
RESISTIVE
LOAD
LAMP LOAD
INDUCTIVE
LOAD
MOTOR LOAD
NO
NC
NO
NC
NO
NC
NO
NC
125 VAC
15A
3A
1.5A
15A
5A
2.5A
250 VAC
15A
2.5A
1.25A
15A
3A
1.5A
500 VAC
10A
1.5A
0.75A
6A
1.5A
0.75
8 VDC
15A
3A
1.5A
15A
5A
2.5A
14 VDC
15A
3A
1.5A
10A
5A
2.5A
30 VDC
6A
3A
1.5A
5A
5A
2.5A
125 VDC
0.5A
0.5A
0.25A
0.05A
0.05A
0.05A
250 VDC
0.5A
0.5A
0.25A
0.03A
0.03A
0.03A
SWITCH
TYPE
CONTACT
SWITCHED
POWER
SWITCHED VOLTAGE
MAXIMUM
SWITCHED CURRENT
(RESISTIVE)
CARRY
CURRENT
BREAKDOWN
VOLTAGE
TYPICAL
APPLICATIONS
DRY CONTACT
REED SWITCH
S.P.D.T BREAK
BEFORE MAKE
20W / VA
MAXIMUM
140V AC
150V DC
1 AMP
MAXIMUM
2 AMP
MAXIMUM
200V MINIMUM
PLC, TELEMETRY & GENERAL
LOW VOLTAGE CONTROL
APPLICATIONS
The reed switch models are supplied with a high compliance single pole double throw reed switch suitable for all low wetting current and low voltage applications. Such
applications include PLC control, signalling in telemetry systems and relay logic circuits.
Note:
the reed switch models are not suitable for use with inductive loads such as
contactors or high wattage relays.
ELECTRICAL DATA REED SWITCH MODELS
Select a location for the flow switch in a straight run of pipe, ideally with five pipe diameters of straight pipe either side of the switch. This will ensure a linear non turbulent flow acts
against the paddle of the switch. Do not install the flow switch in any location likely to expose it to turbulence, such as close to valves, pumps or pipe bends The idea is to install the
switch in a location where there is a smooth flow of liquid past the paddle, and to obtain a stable non-chattering response from the flow switch. The F21 flow switch can be mounted in
either the suction or discharge pipe of a pump, the switch will work equally well in positive or negative pressure applications.
The F21 flow switch has an extra long paddle so it can be used in large diameter pipes. The paddle will require trimming if the flow
switch is to be used in smaller diameter pipes. The paddle can be cut and shaped as required using tin snips or a hacksaw. Note, the
paddle can be cut both in length and if required, in width. Many installers maintain a more stable flow response can be obtained by
narrowing down the paddle and avoiding turbulence close to the walls of the pipe. The F21 flow switch can be installed in any required
orientation except on the under side of horizontal pipes.
Depending on the thread on the switch, a 25 mm, 1” BSP or 1” NPT threaded socket must be provided on the piping, to fit the flow
switch. This may be a tapping saddle or a pipe tee fitted with a threaded reducing bush, or a socket welded directly to the pipe. Ensure
that whatever fitting is used, sufficient clearance is allowed for the free movement of the paddle. Normally a clearance to the full inside
diameter of the 1” pipe thread will be required. The F21 flow switch can be installed in a 1” pipe socket attached to a short stand off
pipe, at 90° to the main pipe. This method of mounting increases the sensitivity of the switch to low flows due to the extra leverage
against the tip of a longer paddle. If this mounting method is used make sure to leave extra clearance to allow for the full arc movement
of the longer paddle.
Use a suitable thread sealant and tighten the switch into the socket using the spanner flats provided on the switch body. Do not tighten
the switch into its socket by twisting the electrical housing of the switch, as damage to the flow switch may result. Align the flow switch
squarely to the axis of the pipe, with the direction of flow arrow on the side of the switch body parallel to the axis of the pipe and aligned
in the direction of flow. The F21 will not function correctly unless alignment is correct. When installing the flow switch in vertically
aligned pipework, the sensitivity of the switch will be slightly increased; it will detect lower flows when flow is downward, and the
sensitivity will be slightly decreased when flow is upward. This is due to the effect of gravity on the dead weight of the paddle itself.
This effect is more noticeable in larger pipes and low flows where long paddles may be used.
WARNING
Please read these installation and operating instructions fully and carefully before installing or servicing this level switch. The F21 Series flow switch is
mains voltage device. Death or serious injury may result if this switch is not correctly installed and operated. All electrical work must be performed by
a fully qualified and licenced electrician.
Vendor Manual - Heavy Duty Flow Switch - Kelco - Model F21 - Installation Operation and Maintenance Manual
Q-Pulse Id: VM465
Active: 27/10/2014
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