Kobold VKM Vicositiy Compensated Flowmeter/Switch

Wiratama Mitra Abadi 01 21.31 flow measurement,

Kobold VKM Viscosity Compensated Flowmeter/Switch has a spring loaded float, which slides within a cylindrical measuring tube and has an integral orifice that is believed to be unique. This and other design features mean that it has for the first time become possible to create a flowmeter and switch which fully compensates for viscosity and to a large extent for density even with very low flows.

The float of these patented devices contains a permanent magnet which actuates a potential free bistable reed contact mounted outside the flow thus ensuring her-metic separation between the medium and the electrical contact system. The contact is embedded within a height-adjustable plastic housing to prevent damage to the contacts by mechanical action or aggressive atmospheres.

As the medium enters the instrument the float rises. Once its magnetic field reaches the contact tips of the reed switch the contact closes. As the flow increases the float rises further until it reaches its stop. This prevents the float from going beyond the contact range of the magnetic operating tube, that is, the contact remains closed thus ensuring bistable switching.

Features

Applications

Lubrication circuits
Hydraulics
Paper-making machines
Extruding plant
Machine tools
Printing presses
Oil lubrication circuits

Specifications

Technical Details

Body:
VKM- x1..: brass, nickel-plated
VKM- x2..: stainless steel 1.4301
Screwed fitting:
VKM- x1..: brass, nickel-plated
VKM- x2..: stainless steel 1.4301
Float:
VKM- x1..: brass, nickel-plated
VKM- x2..: stainless steel 1.4301
Orifice: stainless steel 1.4310
Spring: stainless steel 1.4310
Magnet: oxide ceramics
Seals:
VKM-x1..: NBR
VKM-x2..: FPM
Max. temperature: +100°C
Max. pressure:
VKM- x1..: 250 bar
VKM- x2..: 350 bar
Installation position: any
Basic accuracy: ± 4% of full scale (with a viscosity of 105 mm2/s)
Measuring error due to change in viscosity: for changes in viscosity within 1...540 mm2/s the additional deviation is ± 5% of full scale max.
Viscosity range:
1... 540 mm2/s
VKM-xx01 (70...400 mm2/s)

Viscosity Compensation

If the viscosity changes from 1 mm2/s to 540 mm2/s the indicated value is still accurate within ±5%, even with very low flows, for example, 0.1 l/min. Comparable devices, for instance, conventional float-type flow meters, are, if the viscosity changes to such an extent, subject to indicating errors up to 2500%, especially with comparable low flows. Other instruments with spring-loaded floats, which are allegedly viscosity compensated, still produce indicating errors of more than 500% with the same change in viscosity and a flow of 0.1 l/min.

Thanks to the virtually perfect viscosity compensation and good density compensation the flowmeters and switches of the latest generation are suitable both for water and highly viscous oil, without having to change the scale and without readjustment. This constitutes an extremely important advance especially in the critical area of oil lubrication circuits where measurement and switching are necessary at changing media temperatures.