Kelco Heavy Duty Level Switches
Installation and Operating Instructions for L26 Series Level Switches
Please read the installation information carefully and fully before attempting to install or service this level switch

APPLICATION

The L26 series Level Switch is a side entry float level switch designed to be mounted in a threaded socket fixed to the side of the tank. The switch wil provide an ON or OFF signal when liquid reaches the level of the float. The arm of the float switch is of suffient length to clear the inner walls of the majority of tanks.

The switch is available with an all ABS body, in which there are no metal parts in contact with the liquid being sensed. The switch is suitable for applications involving super pure water, water, sea water and a variety of chemical solutions including acids and alkalis. The switch can also be supplied with a 316 stailess steel or bronze body. Metal body switches are suitable for secure applications where there may be a danger of vandalism or fire.

Typical tank application with the float switch screwed into a 25mm (1") BSP cosket fixed to the side of a tank.
figure 1

ENVIRONMENT

The L26 Level Switch has a fully weatherproof housing made from high quality ultraviolet stabilized ABS. The switch is designed for fully exposed outdoors applications. The switch may be used on liquids with temperatures from -20°C to +80°C. Thw switch should not be used with liquids which contain solids or precipitates which are likely to deposit or jam in the arm housing of the switch.

The standard L26 Level Switch may be used in pressurized tanks or vessels in which the pressure does not exceed 10 bars (145 P.S.I.). The same pressure rating also applies to switches with stainless or bronze bodies, due to the pressure limitations of the float.

INSTALLATION

This switch is intended to be mounted in the horizontal plane in the side of the tank or liquid container.

A 25mm (1inch BSP) socket must be provided on the side of the tank at the precise level at which the switch operation is required. The socket must have a full bore diameter clearance through the side of the tank equal to the inside diameter of a 25mm (1 inch) B.S.P. thread. This is to allow clearance for the switch arm and float, and to allow the switch to be extracted or fitt flygted.

The level switch should be screwed into the socket using thread tape. Correct orientation is with the cable entry port pointing vertically down, on the under side of the switch.

ELECTRICAL INSTALLATION

All electrical work associated with this Flow Switch must conform to the relevant local codes and must be carried out by qualified persons only.

L26 level switches may be supplied with one of two different single pole double throw microswitch. The electrical rating of the particular microswitch is set on a label located inside the lid of the electrical housing. The standard microswitch is suitable for the majority of simple control applications including control of relays, contactors, PLC's, timers and low wattage motors. The optional heavy duty microswitch which has tungsten carbide contacts is intended for the direct control of high amperage or high amperage or highly inductive loads.

For testing or commisssioning purposes the arm of the microswitch may be depressed manually to simulate actuation of the switch.
Cable entry is via the built in cable gland located on the underside of the switch body. The cable gland is supplied with rubber boots for 10mm and 6mm diameter cable. These are fitt flygted one inside the other. In addition, if the cable gland assembly is removed the thread in the body is M20 by 1.5mm, and will directly accept 20mm conduit connections.

When  wiring this level switch take care to ensure wires ar laid tidily around the side of the microswitch and kept clear of the microswitch arm. Wire lying against the microswitch arm will prevent the switch from operating correctly.

ADJUSTMENT

The L26 Level Switch uses a system of magnets acting in opposition to counterbalance the weight of the float arm. This system allows a relatively small float to be employed, which will fit through the bore of a 25mm BPS socket.

Located on the top of the switch is a hexagonal headed dust cap. Removal of this cap exposes a screw which adjusts the amount of magnetic repulsion acting on the float arm. As supplied by the factory the screw is wound fully in and the force acting on the float arm is at its maximum. This setting can be altered by winding the screw outward by up to four turns. The effect of winding the screw outward is to increase the weight of the float, that is, the float will float with less volition the further out the screw is wound.

For the vast majority of applications it should not be necessary to alter the setting of the screw. Winding the screw outward effectively reduces the buoyancy of the float. By winding the screw outwards a dampening effect can be achieved, which reduces the tendancy for the float to bounce about in tanks with slight turbulance, thus avoiding false signalling from the switch.

MAINTENANCE AND REPAIRS

The L26 Level Switch is fully serviceable and repairable in the field. All the parts of the switch are available as spare parts from the manufacturer. There are no special tools required to overhaul this level switch.

When depressing the microswitch are to simulate operation of the switch, for example when commissioning a system, do so with care. Do not bend or distort the microswitch arm. The arm has been preset by the manufacturer so the precise point at which the switch operates is as close as possible to the home face of the housing. Heavy handling or undue pressure applied to the switch arm can distort the arm and render the switch inoperable. If the microswitch has to be replaced, or if the arm is accidently bent or damaged, the switching point will have to be re-established, by careful manipulation of the switch arm. Position the microswitch so it just switches as the arm approaches to within 1mm of the home facce of the housing. Once you have established the exact switching point, lock up the microswitch retaining screws firmly so the switch can't move and thus alter the switching point.
PLEASE NOTE: THE ULTRASWITCH L26 LEVEL SWITCH IS THE SUBJECT OF PATENT AND TRADEMARK APPLICATIONS IN BOTH AUSTRALIA AND ABROAD.

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29/07/03