PLEASE NOTE:
Kelco Engineering Pty Ltd reserves the right to change the specification of this product without notice. Kelco Engineering Pty Ltd accepts no liability for
personal injury or economic loss as a consequence of the use of this product. All rights reserved. Copyright Kelco Engineering Pty Ltd ©2011.
KELCO
Engineering Pty Ltd
ABN 20 002 834 844 Head office and factory:
9/9 Powells Road Brookvale NSW 2100 Australia
Postal Address: PO Box 496 Brookvale NSW 2100 Australia
Phone: +61 2 9905 6425 Fax: +61 2 9905 6420
Email: sales@kelco.com.au Web: www.Kelco.com.au
©2011 Kelco Engineering Pty Ltd
MADE IN AUSTRALIA BY
MAINTENANCE
ELECTRICAL
The F21 flow switch is available in one of two basic configurations. The standard
version of the flow switch is supplied with an SPDT microswitch fitted. A special reed
switch version of the flow switch is also available for low power applications. The
model number of the switch is located on a label inside the switch lid. The standard
flow switch houses a magnetically coupled high current high voltage single pole
double throw microswitch that is suitable for most general-purpose control circuit
applications at any voltage up to 500VAC. The special reed switch version of the
F21 houses a gas filled reed switch that provides a single pole double throw break
before make action. The cable gland on the F21 flow switch is threaded M20 and
will accept standard M20 conduit bushes in addition to flexible cable. When wiring
an F21 flow switch, ensure the lid and cable gland are securely tightened and in fully
exposed locations use secondary precautions such as cable drip loops to make sure
no water can enter the switch housing.
If the F21 flow switch is correctly installed and if the process liquid is compatible with
the materials of construction of the switch then a very long maintenance free service
life can be expected. Factors that may contribute to early failure of the F21 flow
switch include excess temperature, excessive pressure or electrical loads in excess
of the switch’s rating. Should service be required, an exploded view of the flow
switch is included to show the main components and how they fit together. The F21
is a very simple switch to service, and all components are available as spare parts.
HAZARDOUS APPLICATIONS
The F21 flow switch can be used in hazardous areas. The flow switch is classed as a simple device and does not contain components capable of storing or producing an
electric charge. As a simple device the F21 can be used in hazardous applications provided an intrinsically safe barrier (a zener barrier) isolates it.
PADDLE TRIMMING AND FLOW SENSITIVITY
There are two methods of setting the sensitivity of the F21 flow switch. By far the
most effective method is by the correct trimming of the paddle. For fine tuning, a
sensitivity adjustment screw is provided, as shown in the accompanying drawing.
As supplied by the factory, the sensitivity screw is wound fully in, and is set to least
sensitivity. The adjusting screw can be wound out, and the sensitivity slightly
increased. The maximum effect is achieved with the screw wound out to a point
where the screw head is 4mm in from the face of the switch body.
By far the best way to set the F21 flow switch is to make a judgment on the likely flow
rate in the pipe, and to trim the paddle accordingly. If the flow is going to be high
then trim the paddle fairly short, and if you know the flow rate will be low then leave
the paddle as long as possible. If the flow rate is unknown then generally trimming
the paddle to half way across the pipe will achieve a satisfactory compromise and
will work well. Trimming the paddle is a compromise between sensitivity to the duty
flow and stress on the intruding paddle. Fluid flow generates force, and a certain
minimum amount of force is required by the flow switch in order to function.
Excessive force however can bend or break paddles.
The exact flow rates required to actuate the F21 will depend on many variables such
as turbulence, liquid viscosity and the exact area of the paddle face exposed to the
flow. For an accurate estimation of the switching point for any given paddle size, an
online flow calculator is available at www.kelco.com.au
WARNING
All electrical work associated with the F21 Series flow switch must be
carried out by qualified electrical personnel and all electrical work must
conform to AS/NZ (or equivalent) standards and to local wiring rules.
After installing or servicing this flow switch always replace its lid and
fully tighten its lid screw. Also ensure the cable gland is fully tightened.
Never leave the lid off the level switch for extended periods. Without its
lid in place this level switch is not water resistant and presents a potential
shock hazard. Take great care not to splash water onto the inside of the
level switch’s electrical housing when the lid is not in place. Without its
lid the level switch is not weather or insect proof and presents a potential
shock hazard that may result in death or serious injury.
WARNING
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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