L SeriesSide-Entry Level Switch

Side-entry float-arm level switch for tank and chemical-tank level control. Polypropylene or 316 stainless construction with a polypropylene float, 1" BSP / NPT process connection. 5–500 V AC, 15 A S.P.D.T. micro-switch (L-H) or low-voltage gold-contact micro-switch (L-L), both with a built-in manual override.

Features

5 to 500 V AC, 15 A S.P.D.T. micro-switch (L-H)
Low-voltage gold-contact model available (L-L)
316 stainless or polypropylene models
Available with 1" BSP or NPT thread
Manual override built in
Modular construction — swap electrical without disturbing pipework
High-pressure 400 bar / 5800 psi models available (stainless)
Seal-less magnetic drive
Weatherproof IP67 housing
Easily serviceable

The L Series is a side-entry float-arm level switch for tank-side mounting — a reliable, accurate and low cost solution to tank level control. Tip of the arm is free to travel vertically 45 mm each side of horizontal centre; the switching point is in the middle of this travel and occurs ±2° around horizontal. Available in all-thermoplastic construction or in a combination of 316 stainless steel and polypropylene — the same modular electrical housing as the F Series, but with a horizontal float arm instead of a paddle. Supplied with a 500 V rated S.P.D.T. microswitch for general control circuit use (L-H), or an S.P.D.T. gold contact microswitch for PLC, telemetry and other low voltage, low current applications (L-L). Built tough to give a long, reliable service life in the most arduous applications. Manual override built into all models.

More Information

Ordering — Available Models

Model Number	Description
L-H-25B	Standard SPDT, 1" BSP, polypropylene wetted parts
L-H-25N	Standard SPDT, 1" NPT, polypropylene wetted parts
L-H-25B-SS	Standard SPDT, 1" BSP, 316 stainless steel process connection (high pressure), polypropylene float and other wetted parts
L-H-25N-SS	Standard SPDT, 1" NPT, 316 stainless steel process connection (high pressure), polypropylene float and other wetted parts
L-L-25B	Low-voltage gold-contact model (L) — Standard SPDT, 1" BSP, polypropylene wetted parts
L-L-25B-SS	Low-voltage gold-contact model (L) — Standard SPDT, 1" BSP, 316 stainless steel process connection (high pressure), polypropylene float and other wetted parts
L-L-25N-SS	Low-voltage gold-contact model (L) — Standard SPDT, 1" NPT, 316 stainless steel process connection (high pressure), polypropylene float and other wetted parts
L-L-25N	Low-voltage gold-contact model (L) — 1" NPT, polypropylene wetted parts

Operating Limitations

Maximum operating pressure (static or dynamic) at ambient temperature	Polypropylene process connection: 18 bar / 261 psi. Stainless process connection: 400 bar / 5800 psi
Minimum burst pressure at ambient temperature	Polypropylene process connection: 45 bar / 652 psi. Stainless process connection: 500 bar / 7215 psi
Maximum operating temperature	Polypropylene process connection: 60 °C (see pressure de-rating). Stainless process connection: 80 °C / 176 °F
Pressure de-rating (all-polypropylene models)	Maximum operating pressure must be linearly de-rated as operating temperature is increased, so that at 60 °C (140 °F) the maximum permissible operating pressure does not exceed one bar (15 psi) absolute
Minimum operating temperature	-20 °C / -4 °F (both process connections)
Ingress protection rating	IP67
Clearance above and below the switch centre line	25 mm minimum, for free movement of the float

Electrical Data

L-H switch type	S.P.D.T. microswitch for general control circuits up to 500 V AC — ideal for pump starters, relay logic, contactors and timers
L-H voltage range	5 to 500 V AC (minimum load 160 mA at 5 V DC)
L-H direct motor control	Pump motors up to ¼ HP (approx. 185 W) at 240 V AC. For larger motors use a contactor or relay.
L-H maximum switched current	15 A (10 A at 500 V AC). Do not apply maximum voltage at maximum current across the switch contacts.
L-H current rating at 125 V AC	Non-inductive loads: resistive 15 A; lamp 3 A (NC) / 1.5 A (NO). Inductive loads: inductive 15 A; motor 5 A (NC) / 2.5 A (NO).
L-H current rating at 250 V AC	Non-inductive loads: resistive 15 A; lamp 2.5 A (NC) / 1.25 A (NO). Inductive loads: inductive 15 A; motor 3 A (NC) / 1.5 A (NO).
L-H current rating at 500 V AC	Non-inductive loads: resistive 10 A; lamp 1.5 A (NC) / 0.75 A (NO). Inductive loads: inductive 6 A; motor 1.5 A (NC) / 0.75 A (NO).
L-H current rating at 8 V DC	Non-inductive loads: resistive 15 A; lamp 3 A (NC) / 1.5 A (NO). Inductive loads: inductive 15 A; motor 5 A (NC) / 2.5 A (NO).
L-H current rating at 14 V DC	Non-inductive loads: resistive 15 A; lamp 3 A (NC) / 1.5 A (NO). Inductive loads: inductive 10 A; motor 5 A (NC) / 2.5 A (NO).
L-H current rating at 30 V DC	Non-inductive loads: resistive 6 A; lamp 3 A (NC) / 1.5 A (NO). Inductive loads: inductive 5 A; motor 5 A (NC) / 2.5 A (NO).
L-H current rating at 125 V DC	Non-inductive loads: resistive 0.5 A; lamp 0.5 A (NC) / 0.5 A (NO). Inductive loads: inductive 0.05 A; motor 0.05 A (NC) / 0.05 A (NO).
L-H current rating at 250 V DC	Non-inductive loads: resistive 0.25 A; lamp 0.25 A (NC) / 0.25 A (NO). Inductive loads: inductive 0.03 A; motor 0.03 A (NC) / 0.03 A (NO).
Microswitch approvals (L-H and L-L)	UL1054 (File No. E41515), CSA C22.2 No.55 (File No. LR21642) and EN61058-1; CE marked
L-L switch type	Gold contact microswitch, S.P.D.T., gold alloy contacts, so it switches reliably at the low wetting currents of PLC inputs, telemetry and relay logic. Not suitable for inductive or capacitive loads such as contactors and relays. Loads above the rating will damage the switch.
L-L rated current (resistive)	0.1 A at 125 VAC; 0.1 A at 8, 14 and 30 VDC
L-L inrush current	0.1 A maximum (NC and NO)
L-L minimum applicable load	1 mA at 5 VDC
L-L operating range (micro load)	5 to 30 V, 5 to 800 mW (26 mA maximum at 30 V)
L-L contact resistance	50 mΩ maximum (initial)
L-L typical applications	PLC, telemetry and low voltage control

Dimensions

Typical Applications

Tank and liquid level control; low-level protection for pumps; level control in water treatment; chemical-tank level monitoring.

Suitable Liquids

The L Series has been specifically designed for use in both water and aggressive chemical solutions. The process connection is polypropylene or 316 stainless steel; the float and all other wetted parts are made from polypropylene and glass reinforced polypropylene. The all-polypropylene models are suitable for a wide range of liquids including potable water, sea water, acids, bases, ground water and many chemical solutions containing dissolved mineral salts. The switches should not be used in organic solvents. If there is any doubt about the suitability of the switch for a specific application, contact Kelco ([email protected]) before installing it.

Installation

Install the switch in a tank socket on the side wall of a tank (or riser pipe), in the horizontal plane, with the float arm rising and falling vertically. It needs a minimum of 25 mm of clearance above and below its centre line axis for free movement of the float. The float passes through the inside diameter of a standard pipe thread socket, so the switch can be installed from the outside of the tank. Apply thread tape or sealant to the thread and screw the switch into the tank socket using the spanner flats on the process adaptor — never by twisting the electrical housing — leaving a gap of approximately 4 mm between the end of the thread and the face of the tank socket. The cable entry must be on the underside of the switch, pointing straight down. Do not install the switch where the pressure or liquid temperature is greater than the operating limits, do not expose it to freezing (lag the tank and switch where low temperatures will be encountered) and do not use it in hot liquid applications: do not exceed 60 °C for the all-polypropylene model or 80 °C for the stainless model.

Hazardous Areas

The L-H is not certified for use in hazardous areas and must not be installed in any area classified as hazardous under AS/NZS 60079.10 (Zone 0, 1, 2, 20, 21 or 22). The L-L is simple apparatus under AS/NZS 60079.11 and may be used in a hazardous area only as part of an intrinsically safe circuit, connected through suitably certified associated apparatus. It is not Ex certified in its own right. The associated apparatus must not exceed Uo ≤ 30 V, Io ≤ 100 mA. The full conditions of use are given in the installation sheet.

Manual Override

All L-H and L-L models include a manual override button. Press to switch on regardless of float position — useful for testing and commissioning.

Safety and Wiring

The L Series level switch is a mains voltage device: all electrical work must be performed by a fully qualified and licensed electrician. Check the model number on the label inside the lid before wiring, and confirm the load is within the electrical ratings — the L-L switch is easily damaged by overload. The terminals are marked C (common), NO (normally open) and NC (normally closed); in a two-wire installation one wire is always connected to common and the switch wire to either NO or NC, depending on the application. Without its lid in place the switch is not water resistant, not weather or insect proof, and presents a potential shock hazard that may result in death or serious injury. After wiring or servicing, always replace the lid and fully tighten its securing screw and the cable gland, and never leave the lid off for extended periods or splash water into the open housing.

Serviceability

Fully field-serviceable. The electrical housing detaches from the wet-end via a single screw without disturbing pipework. Low-maintenance: provided it is correctly installed, the switch should function properly for many years. Pressures and temperatures in excess of its rating, and electrical loads greater than the limits of its built-in microswitch, may reduce its useful life. Replacement floats and switches available from Kelco Engineering or your distributor.