OPTISWITCH 5000 Series Vibration Level Switches

The OPTISWITCH series from KROHNE is a family of advanced vibration level switches with extendable probes designed for reliable point level detection of liquids, even in demanding process conditions.

• OPTISWITCH 5100 – standard industrial version with wide choice of process connections and electronics, density ≥ 0.5 g/cm³.

• OPTISWITCH 5150 – hygienic polished version for food, beverage, and pharmaceutical applications.

• OPTISWITCH 5200 – rod extension up to 6 m for general industrial processes.

• OPTISWITCH 5250 – hygienic version with rod extension up to 6 m for food & pharma.

• OPTISWITCH 5300 – designed for extreme conditions (high/low temperature & pressure), extension up to 3 m, density ≥ 0.47 g/cm³ (optionally ≥ 0.42 g/cm³).

Operating Principle

A piezoelectric drive excites the tuning fork or rod to vibrate at its resonant frequency ≈ 1.4 kHz. When the probe contacts liquid, the vibration is damped, changing amplitude and frequency. The electronics immediately detect this change and issue a switching command (relay, transistor, or NAMUR). The measurement is independent of conductivity, foam, adhesion, or density (down to 0.42 g/cm³).

General Technical Specifications

All models feature a compact stainless-steel housing with IP66/67 rating, power supply 10–30 V DC or 90–253 V AC, and power consumption < 1 W. Process temperature: –196 °C to +450 °C (5300) or –50 °C to +250 °C (other models); pressure from –1 to 160 bar (5300) or up to 64 bar (others). Insertion length: up to 6 m (5200/5250), up to 3 m (5300), or standard compact (5100/5150). Wetted parts: stainless steel 1.4404/1.4571, optionally polished Ra < 0.76 µm for hygienic use. Outputs: relay (SPDT/DPDT), transistor (Puls), NAMUR, frequency, optional HART or IO-Link. Switching accuracy ±1 mm, response time < 0.5 s. Explosion protection: ATEX, IECEx, FM, CSA (up to Zone 0/20). Hygienic certifications (5150 & 5250): EHEDG, 3A, FDA-compliant materials.

Main Application Areas

• Chemical, petrochemical, and oil & gas industries (aggressive liquids, high-pressure vessels)

• Power plants, water & wastewater (level monitoring in tanks, overfill & dry-run protection)

• Food & beverage, dairy, and pharmaceutical industries (hygienic tanks and pipelines)

• Applications requiring long insertion lengths or very low-density liquids (≥ 0.42 g/cm³)

Advantages of OPTISWITCH Vibration Level Switches

• No moving parts → virtually maintenance-free operation

• Insensitive to buildup, foam, condensation, and external vibration

• Works reliably with extremely low-density liquids (down to 0.42 g/cm³) and in extreme temperatures/pressures

• Long reach (up to 6 m) enables installation in hard-to-access locations

• Fast response and excellent repeatability

• Simple one-button or adjustment-free commissioning

• Full hazardous-area approvals and hygienic certifications where required

• Extremely long service life (MTTF > 50 years)

• Compact design, flexible process connections, and low total cost of ownership