CR22 MicrodébitDétecteur MicroFlow — bas débit, résistant aux produits chimiques
Capteur de débit en ligne compact conçu pour détecter de très faibles débits — moins de 500 mL par heure. Idéal pour la détection de perte de débit dans les systèmes de dosage et d’injection chimique. Corps PVC avec joints Viton ; convient aux réactifs courants de traitement d’eau.
Caractéristiques
- Détecte des débits inférieurs à 500 mL par heure
- Débit continu maximal de 4 L/min
- Adapté aux débits pulsés ou continus
- Convient aux tubes et tuyauteries de 6 mm à 20 mm
- Toutes les pièces en contact avec le fluide en UPVC, joints Viton
- Détecteur compact à montage vertical
- Pression nominale 18 bar (260 psi)
- Réponse rapide à la perte de débit
- Facile à installer et à entretenir
- Étanche aux intempéries
Le CR22 fonctionne selon le principe du piston déplacé. Le liquide de procédé qui traverse l’interrupteur vers le haut soulève un piston de précision ; à chaque levée du piston, un aimant scellé à l’intérieur actionne une ampoule reed externe. Le CR22 peut être configuré en interrupteur normalement fermé ou normalement ouvert, répondant soit au débit, soit à la perte de débit. Tel que livré, il est normalement ouvert et se ferme en réponse au débit ; l’inversion des adaptateurs d’entrée et de sortie inverse cette fonction.
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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.
Maintenance
Le CR22 est entretenable sur site. Le module électrique à ampoule reed peut être retiré et inversé, et la liste des pièces de rechange comprend la tête de capteur, le corps, le piston, les joints toriques Viton, les adaptateurs d’entrée et de sortie, les écrous de raccord, les embouts de tuyauterie, les adaptateurs de tube et les supports de montage mural. Pièces de rechange, y compris joints et pistons de remplacement, disponibles auprès de Kelco Engineering ou de votre distributeur.
