Overview

MEISTER DKM-series flow switches are mechanical paddle/rotor (float) type monitors designed for hydraulic oil, lubrication oil and other liquid media. A viscosity-compensated mechanism keeps the switching point stable as oil temperature and viscosity change, while a magnetic coupling triggers a wear-free reed contact. This guide covers selection, installation and commissioning of DKM flow switches.

1. How it works

A float/rotor is suspended in the flow and pushed by the medium. Its movement is transmitted through a magnetic coupling to a reed switch — a non-contact, wear-free trigger. The built-in viscosity compensation reduces the influence of oil temperature and viscosity variations on accuracy.

2. Series overview and specifications

• DKM-1: 0.5–110 L/min; brass (MS) 250 bar / stainless steel (VA) 300 bar.

• DKM-2: 0.5–7 L/min, optimised for small flows and high-viscosity media.

• DKM/A: 0.1–110 L/min with integrated flow display and switching.

Common specifications: medium hydraulic/lubrication oil 30–600 cSt; temperature -20 °C to 120 °C (optional 160 °C); accuracy ±10% FS; output single-pole double-throw (SPDT) dry contact 250 V / 3 A; protection IP67; connections G1/4–G1 female thread; optional ATEX version for hazardous areas.

3. Selection steps

• Match the medium: 316L stainless steel for corrosive fluids; brass for mineral oil; POM float and FKM seal as standard (EPDM/NBR on request).

• Flow set point: set the trip point within 20%–80% of the measuring range to avoid dead band and false triggering.

• Pressure and temperature: standard up to about 250–300 bar; specify high-temperature or high-pressure versions when required.

• Connection: G threads (G1/4–G1) for small bores; PN40 flange for DN50 and larger.

• Output: dry contact for PLC on/off; IO-Link or 4–20 mA for remote monitoring.

• Certification: ATEX for explosive atmospheres; 3A / USP Class VI for food and medical applications.

4. Installation and wiring

• Flow direction: vertical installation is recommended with flow bottom-up; never install inverted.

• Straight runs: keep upstream at least 5 DN (DKM/A) or 4 DN (other types) and downstream at least 2 DN; keep away from pumps and compressors, use damping brackets if needed.

• Filtration: for lines up to DN25 add a 100 μm filter upstream to prevent rotor/paddle jamming.

• Sealing and torque: use PTFE tape on threaded joints; tighten to about 10–12 N·m for G1/2 and about 15–18 N·m for G3/4.

5. Maintenance and troubleshooting

Check monthly for leakage and rotor/paddle freedom; clean the float and paddle quarterly; calibrate the set point annually against a reference flow meter (re-adjust if deviation exceeds ±5%). Common faults: no output (flow below set point, burnt contact, wrong wiring), signal chatter (entrained air, turbulence, vibration — add bleed valve, lengthen straight runs, add damping), and jamming (contamination — flush line and add filter).

EFFSEN supplies the full MEISTER DKM range with selection and application support, fast delivery and worldwide shipping for hydraulic and lubrication monitoring.