D. B. Instruments & Controls

Dahisar, Mumbai, Maharashtra

Level transmitter works on the principle of reed resistance/permanent magnet basis. Reedswitches function like the center arm (as shown in fig. 1) of a potentiometer. As per liquid level float moves up or down, magnet inside the float operates the reedswitches thereby causing a change in resistance value. Change in the resistance is measured by the electronics unit and conditioned as a current output of 4 to 20 mA. Signal conditioner is head mounted and of 2-wire loop powered suitable for 12 to 24 VDC giving output of 4 to 20 mA.

Model (VMT-04-F65-AW) , (VMT-04-F92-AW)top mounted magnetic reed/resistance cascade type loop powered 2 wire level transmitter. Process Connection flange 78 or 120 mm diameter with 4 bolt holes of 6mm or 14 mm dia on 65 or 92 mm PCD respectively. Wetted parts flange & float stopper in SS 304. Float material SS 316L and diameter 41, 53 or 68 mm. Operating pressure 10kg/sq.cm and Temperature 125 deg.C. maximum.

• Reedswitches are hermetically sealed-in glass under an inert gas and therefore protected from contamination.
• Reedswitches used by us are suitable for maximum working voltage of 150 VDC and current 1 Ampere. But in our circuitry they are subjected to maximum of 3 VDC and current 1 mA in case of resistance output and maximum of 24 VDC and 20 mA when used in conjunction with a signal conditioner for current output. This ensures long life of the product.
• Reedswitches are UL approved and ISO certified for quality management.
• Operating temperature range of reedswitches are -40 deg. C. to 125 deg. C.
• Reed Switches are enclosed in a moulded glass filled nylon capsule and therefore protected from mechanical shocks or damage. Moreover the stainless steel float-guide pipe, containing the PCB of reedswitches and resistances, is solidly filled with MgO Powder. Hence this is suitable for sub zero temperatures.
• Reedswitches are protected against mechanical damage and contact corrosion & vibration.
• Since an outer protection tube is provided (for applications like LPG, where external cage is not possible) the reedswitch sensor assembly can be replaced without disturbing the process.
• Since the float is of 200mm dia with specific gravity -0.4 (for LPG) it will have higher buoyant force. For standard applications float shall be of 48 mm Or 68 mm in diameter.
• Above all float is the only moving part. No wear and tear.

• Applicable in environment with high temp., high pressure, strong acid, strong alkaline and hazardous locations.
• Multiple applications for textile dyeing, sewage water processing, power generating, boiler and petrochemical industries.

Utilising the basic principle of - liquids find their level - tubular level gauges have been the most preferred and economical means of direct liquid level indication since time immemorial. Various means of glass tube protections- 3 plate glass protection, 3 guard rods, pipe guard or C-channel protections are in popular use. Our level gauges have C-channel protection of 2 mm thick sheet metal, making it robust and sturdy.

A black powder coated aluminium engraved scale with white numerals & markings is provided for indication of the level of liquid in millimeter or Litres as required. Scale shall have minimum graduation of 5 mm.

Process connections can be threaded or flanged to customer specifications. Isolating cock valves/needle valves or isolating needle valves with safety ball-check protection to prevent spilling/leakage by automatic shut-off in the event of glass tube breakage- are optional features

• Vent Cock Valve/Drain Cock/Vent & Drain Needle/Ball Valves
• Gauge Isolating Needle Valves.
• Gauge isolator valve: SS 304/316 solid barstock needle valve, offset type with safety ball-check protection and process connection as above (please specify).

Electronic control unit in conjunction with level switches can be used for pump control, opening and closing of electrically operated valves, heaters and or high and low level indication.

The electronic unit Model LC1 FL reduces the voltage and converts it to 5 VDC for operation of reedswitches enhancing their life, above all ensuring operational safety. The LED's in the front panel indicates Main Power Supply On, Pump Start and Stop conditions. The start/stop push buttons in the front panel enables testing of the control unit and also manual start and stop. The control unit has a Change over potential free relay output contact-hold on type. Contact change over takes place between High and Low level only. Relay contacts are rated 5 Amps at 230 VAC. Control action can be reversed at site by changing connections from NC to NO.

For certain applications where high and low level indications are required, 2 separate relay output contacts are provided in the control unit-with LED indications for High, Low and Mains on

Model LC2FL are used in boilers where High and Low Level Contacts are used for Pump start & stop while Very Low Level Contact is used for heater cut off.