AIR FLOW SWITCHES EARLTYPE 167 172 173

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- EARL flow switch type 107 GKL
- EARL flow switch type 31d

Air flow switches
Type 167 for pipes 80x80 mm
Type 172 for pipes DN 80
Type 173 for pipes DN 40

Tough and unaffected by non-adhesive impurities in the medium these flow switches controls the flow of gases regardless of high operating pressures. For units to control the flow of liquids see type 107.

For type 167 the units are mounted by a flanged boss (provided by the installer) either to horizontal pipes or sideways to vertical square channel. Flow direction upwards only with special flange.

The flow switch type 172 and 173 controls the flow of liquids and gases in pipes DN 40 to DN 100. The units are mounted by a flanged boss (provided by the installer) either to horizontal pipes or sideways to vertical pipes with direction of flow upwards only. A special model with balance weight for direction of flow downwards is available (type 172 only).

The specification required for the flow switch depends upon the nominal bore of the pipe on which it is mounted and not upon the connecting flange, e. g. flow switch type 172 DN 100 with connecting flange DN 80 PN 16.

Operation

When the medium enters in the direction of flow indicated by the arrow it moves the vane in the direction of flow.

A permanent magnet is situated at the vane and operates the switch contact. The set point is not adjustable.

Advantages

• The bearing used make the units suitable for use with media containing dust particles.
• Sensitive control for set points from 0.6 m/s.
• Cavity-free construction.
• Suitable for high pressures up to PN 160.
• Explosionproof models available to several standards.
• For high flow velocities or larger line sizes the units are equipped with a stop for the vane.
• Special models available for temperatures up to 250 °C.
• Models available for use in maritime and humid tropical climates.
• Long-term continuity of spares availability.

Suitability

• Flow control in chemical processes.
• Control of exhaust gas in conventional and nuclear power stations.
• Control of undesired back-flow in compressed air installations.
• Flow control in gas supply networks.
• Control of feed and exhaust air in mines.
• Ventilation control in machines or enclosed electrical installations.
• Control of scavenging-air in hazardous areas by means of pressurized apparatus (Ex)p.
• Exhaust gas control in heating installations.
• Suction-sided control of ventilators and compressors.
• Control of two-phase flows.

Models available

• Type 167v for fixed setpoint at decreasing flow of 2.5 m/s.
• Type 172K solid plastic construction for aggressive media.
• Type 172S with special vane, which turns automatically into the direction of flow when higher flow velocities arise thus keeping the pressure loss low.
• Type 172(Ex) explosionproof model EEx de II CT6 according to ATEX
• Type 173 hygienic flow switch for fittings according to DIN 11852....
• Type 173Fl (Ex)i suitable for intrinsically safe circuits with connecting flange DN...PN...,switch housing, terminals and cable entry.
• Tropical model (humid tropical with termites)

The model for use in tropical climates consists of:
Switch housing and flange of sea-water resistant gun metal Rg10; porcelain-insulated electrical terminals and silicone insulated litz wire with woven glass coating.