CR22 MicrovazãoChave MicroFlow — baixa vazão, resistente a produtos químicos
Sensor de fluxo em linha compacto projetado para detectar vazões muito baixas — menos de 500 mL por hora. Ideal para detecção de perda de fluxo em sistemas de dosagem e injeção química. Corpo em PVC com vedações de Viton; adequado para reagentes comuns de tratamento de água.
Recursos
- Detecta vazões inferiores a 500 mL por hora
- Vazão contínua máxima de 4 L/min
- Adequado para fluxos pulsados ou contínuos
- Adequado para tubos e tubulações de 6 mm a 20 mm
- Todas as partes em contato com fluido em UPVC com vedações de Viton
- Chave compacta de montagem vertical
- Pressão nominal 18 bar (260 psi)
- Resposta rápida à perda de fluxo
- Fácil de instalar e fazer manutenção
- À prova de intempéries
O CR22 opera pelo princípio do pistão deslocado. O líquido do processo que passa para cima através da chave levanta um pistão de precisão; cada vez que o pistão é levantado, um ímã selado em seu interior aciona um reed switch externo. O CR22 pode ser configurado como uma chave normalmente ligada ou normalmente desligada, que responde ao fluxo ou à perda de fluxo. Conforme fornecido, ele é normalmente desligado e liga em resposta ao fluxo; inverter os adaptadores de entrada e saída inverte essa função.
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Hazardous Areas
The CR22 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 full conditions of use are given in the installation sheet.
Orientation — must mount vertically
The CR22 must be oriented vertically with flow passing upward through its body. The switch relies on gravity to return its internal piston to the off position when flow stops. If installed in horizontal pipework it will not switch off when flow stops.
Normally-On or Normally-Off
As supplied, the CR22 is normally off and switches on in response to flow. To reverse the function simply unscrew the inlet and outlet adaptors (parts 5 and 6 on the spare parts list) and reassemble with them swapped. The electrical module can also be removed and reversed so the cable enters from either side; reversing the module does not change its electrical function. The electrical module is a slip fit on the switch body and can be rotated to any required position without affecting operation.
Compatible Liquids
Suits clean liquids free from suspended solids larger than 30 µm and free from particulates or sludge residue that may be attracted to magnets, including most mineral salts, many acids and bases. The wetted parts are UPVC with Viton O-ring seals, with no metal parts in the wet area. ‘Ferric solutions, organic solvents, esters and ketones’ in general should not be used. Not suitable for highly viscous liquids or liquids containing materials that tend to crystallise.
Viscosity and Specific Gravity
The sensitivity to flow is not adjustable. In general, liquids of an SG > 1.0 or kinematic viscosity of > 1.0 proportionally increase the sensitivity of the switch and slow down its response time, so less flow is needed to actuate it. Low SG and low viscosity liquids have the reverse effect: the switch is less sensitive, needs a proportionally higher flow to actuate, and responds proportionally faster.
Pulsed-Flow Behaviour
When connected directly to a dosing pump the CR22 normally receives a train of liquid pulses. If the pulse frequency is greater than one every 2 seconds, the switch provides a steady output state. If pulses are slower than one every 2 seconds the switch may respond with a series of on/off signals proportional to the dosing pump’s pulse frequency. When the liquid stops flowing the switch changes state after a delay that depends on the process liquid’s viscosity; for water the delay is approximately 2 seconds.
Installation
Mount in a dosing system directly onto the pump discharge valve, on an adjacent wall or backing board, or directly onto an injection point; mounting at an injection or discharge point makes the switch indicate loss of flow for the whole system, including the pump’s discharge pipework and valves. Two mounting clips are supplied: drill 2 holes 53 mm apart and fix with 4 mm stainless screws (not supplied). For rigid PVC pipework use the PVC pipe spigots, taking care that no solvent or glue enters the switch body. Do not over-tighten the union nuts or the inlet and outlet adaptors, because the switch is sealed by O-rings and over-tightening the inlet adaptor may distort the body and jam the piston. Purge pipework before installing and, if necessary, fit a 30 micron filter on the inlet side. Do not install the CR22 on the suction side of a dosing system, as its flow restriction may cause the pump to cavitate or fail to prime.
Process Liquid Temperature
The operating limits are 0 °C to 60 °C, but in the interest of safety the CR22 should only be used with process liquids that are at or close to ambient temperature.
Reed Switch Protection
The CR22 uses a dry contact reed switch as its primary switching element. Reed switches offer an operating life in excess of 100 million cycles, but care needs to be taken to ensure they are not electrically overloaded. If applied in questionable applications, suitable protection should be added to the control circuit.
Electrical Work
The CR22 microflow switch is a mains voltage device. All mains voltage electrical work must be performed by a fully qualified and licensed electrician and conform to AS/NZS (or equivalent) standards and local wiring rules.
Manutenção
O CR22 está sujeito a manutenção em campo. O módulo elétrico de reed switch pode ser removido e invertido, e a lista de peças de reposição inclui o cabeçote do sensor, o corpo, o pistão, os O-rings de Viton, os adaptadores de entrada e saída, as porcas de união, as pontas de tubo, os adaptadores de tubo e os suportes de montagem em parede. Peças de reposição, incluindo vedações e pistões de reposição, disponíveis na Kelco Engineering ou no seu distribuidor.
