Vibration Type Level Switch - VLS Series

Vibration Type Level Switch - VLS Series. The blade of the probe vibrate on its resonance frequency. When filling material covers the blade of the probe, the vibration stops. This is sensed by the electronic circuitry and the output relay switches. When the blade gets uncovered, the vibration will restart and the relay will switch back.

Vibration Type Level Switch Principle


• Only the tip of the vibrating blade is sensitive and not the base, build-up on the container wall
has no influence on the function of the instrument.

• The shape of the blade and its vibration have a self-cleaning effect.

• No - Moving parts, maintenance required and calibration required

• Unaffected by - Environmental changes (e.g. temperature, pressure, humidity), material
changes, dust clouds and agitation

• Maximum – Versatility

• Design - Single Prong - The single prong design with its sharp edged vibrating blade prevents
material build-up typically associated with the dual prong “tuning fork“ design.

Level Switch Tuning Fork

• The VLS can be used for light material with densities as low as to 10 g/liter. Strong stainless
steel construction makes the VLS tough for the use with heavy materials such as cement.

• Fail-safe - The electronic circuit of the VLS indicates power failure. If power supply fails the relay
drops into alarm condition.


Level Switch Application

The VLS series is a piezoelectric driven vibration type level switch that detects the level in bins, silos and hoppers, filled with grained or powdered materials (bulk solids). The instrument can be used for overfill protection, for high or low level alarm.

VLS designed for the detection of all kind of dry bulk solids, powered grain or granular state The following list shows some of the materials the VLS has been successfully used for:

Powdered Milk
Tea (leaf)
Wood Shavings
Frozen Chips
Glass Ground
Coffee Beans
Granular Plastics
Coffee Ground
Animal Food
Powdered Clay
Carbon Black
Foundry Sand

Because of its maximum versatility, the VLS is ideal for applications where contents change are common. Thus, instrument does not require re-calibration for a new or different material.


Technical Details
Powder coated die-cast aluminum
Protection IP 66 and IP 67
1 cable entry (option: second cable gland)
Power Supply
Wide range power supply: 20 ... 250V AC/DC
Power Consumption
1 potential-free change-over contact (SPDT),
(option: DPDT)
max. switching datas AC: 250V-AC,
8A, 2000VA, cos = 1max. switching datas
DC: 8,0A at 24V-DC / 1,5A at 48V-AC
min. switching datas DC: 24V / 100mA
Time Delay
1 second from stop of vibration
2 to 5 seconds for start of vibration
Probe Material
Stainless steel 1.4301 / AISI 304
Process Connection
VLS100:1” NPTM
VLS200/300/400: 11/2” NPTM
Optional : Screw on flange accordingly to DIN, ANSI or JIS
Max. Load: Max. Vertical and Horizontal Load Upon the End of the Blade
VLS100: 80N
VLS200/300/400: 100N
Max. tensile load of cable VLS400 : 200 kg
LED Indication
(On VLS200, 300 & 400)
Relay On: Red LED continuous blinking
Power On: Red LED
Min. Density of Material
VLS100: 50g/liter
VLS200/300/400: 20g/liter
Max. Pressure Inside Bin
10 bar
Ambient Temperature
Electronic: -20°C ... + 60°C
Process Temperature
Probe: -20°C ... + 80°C
Probe High Temp: -20°C ... + 150°C
Note:Specifications are subject to change without notice.


For all inquiries, you may contact us through Telephone, Email or Live Chat Support.

Operating Hours

Monday to Friday: 8.00am to 5.30pm

Technical Support (After Office Hours)

Tel: (65) 9876 6258

Contact Information

By Phone / FaxBy Email
Tel: (65) 6553 0366
Fax: (65) 6553 0828

Flotech Approvals