Série LMChave de nível com entrada lateral para serviço pesado
Chave de nível com entrada lateral e boia, de grau industrial/mineração — mesma ação comprovada da série L, mas em carcaça de alumínio forjado com conexão de processo em aço inoxidável 316. Boia e braço em polipropileno; microswitch S.P.D.T. 5–500 V CA, 15 A (LM-H) com override manual integrado, ou microswitch de baixa tensão com contatos de ouro (LM-L).
Recursos
- Microswitch S.P.D.T. 5–500 V CA, 15 A (LM-H)
- Modelo de baixa tensão com contatos de ouro disponível (LM-L)
- Conexão de processo em inox 316
- Carcaça super resistente em alumínio forjado
- Override manual integrado
- Modelos 1" BSP e 1" NPT disponíveis
- Acionamento magnético sem vedações
- Carcaça à prova de intempéries IP67
- Fácil manutenção
A série LM é construída robusta para serviço exigente, oferecendo uma solução confiável e precisa para o controle de nível em tanques. Conexão de processo em aço inoxidável 316 + carcaça elétrica de alumínio forjado usinada em CNC + boia e braço em polipropileno. O microswitch S.P.D.T. padrão de 5 a 500 V (LM-H) é adequado para circuitos de controle em geral — ideal para partidas de bomba, lógica de relés, contatores e temporizadores — e o microswitch S.P.D.T. de baixa tensão com contatos de ouro (LM-L) é para CLP, telemetria e controle de baixa tensão. Override manual em todos os modelos LM. A ponta do braço percorre 45 mm para cada lado do centro horizontal; a chave opera a ±2° em torno da horizontal.
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Application
The LM level switch has been designed to operate in water and sea water applications. The process connection is made from 316 stainless steel; the float and all other wetted parts are made from glass reinforced polypropylene.
Switching Point
Tip of the arm travels 45 mm each side of horizontal centre. Switching occurs ±2° around horizontal (2 degrees each side of the horizontal centre line), so the arm movement can be confined to within 3 to 4 degrees each side of horizontal and the switch will still operate properly.
Manual Override
All LM-H and LM-L models include a manual override button. Press to switch on regardless of float position — useful for testing and commissioning.
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 in 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 is greater than the float rating of 980 kPa (100 metres head) or the liquid temperature is greater than 80 °C. Do not expose it to freezing (lag the tank and switch where low temperatures will be encountered), and do not use it in high temperature applications or in water hotter than 80 °C. The stainless body of the switch is rated to withstand 400 bar pressure; however, the float itself is only designed to withstand 100 metres head pressure (980 kPa or 142 psi).
Wiring and Earthing
The LM level switch is a mains voltage device: all electrical work must be performed by a fully qualified and licensed electrician. Check the part number on the label inside the lid before wiring, and confirm the load is within the electrical ratings — the LM-L switch is easily damaged by overload. The terminals are marked COM (common), NO (normally open) and NC (normally closed); for a two-wire connection use COM plus either NO or NC to suit the application. Connect the earth terminal inside the housing — the LM must be earthed when operated at mains voltage. Fully tighten the cable gland nut, check the lid gasket is in place and tighten the lid down: without its lid the switch is not water, weather or insect proof and presents a shock hazard that may cause death or serious injury.
Hazardous Areas
The LM-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 LM-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.
Replacing the Float Arm
The float arm and its associated pivot bearings are replaceable items. Spare assemblies can be obtained from your supplier — please quote the part number of the level switch when ordering. To remove the assembly, unscrew and remove the locking bolt on the side of the process adaptor (right-hand thread), pull the float arm assembly straight out without twisting it, and thoroughly clean the inside of the process adaptor. Replacement arm assemblies are supplied with new bearing shells and a large retaining O-ring: assemble the two bearing shells onto the arm (O-ring groove towards the long end of the arm), fit the large O-ring, align the flat face and location hole of the bearing shell with the locking bolt hole, and push the assembly all the way in to the dead stop. Check or replace the small O-ring under the locking bolt head, apply silicone grease or Vaseline to the bolt thread, then fit and fully tighten the locking bolt. Test the arm by pushing it up and down: it should swing freely and, when pushed to the up position, drop to the off position under its own weight when released.
Manutenção
Totalmente sujeito a manutenção em campo. Um único parafuso acessível externamente libera a carcaça elétrica da parte úmida. O braço da boia e seus mancais de pivô são itens substituíveis: conjuntos de braço de boia de reposição estão disponíveis no seu fornecedor — informe o número de peça da chave de nível ao fazer o pedido. Boias, vedações e chaves de reposição disponíveis na Kelco Engineering ou no seu distribuidor.
