The KOBOLD VKA is a viscosity compensated variable area flow meter that holds its stated accuracy across oil viscosities from 30 to 540 cSt, with no recalibration required. Rated to 3,600 PSIG in economical nickel-plated brass, it is designed for applications where conventional meters either fall short on pressure ratings or require costly materials. It is available as a switch only, a meter only, or a combined meter and switch.
High Pressure Flow Measurement for Viscous Oil Applications
The VKA measures viscous oils across eight flow ranges spanning 2...6.3 GPH up to 8...26 GPM while operating at line pressures up to 3,600 PSIG. Internal modifications limit pressure loss through the meter to 8 PSI at maximum flow while still maintaining a compensated viscosity range of 30 to 540 cSt.
Combining proven, reliable construction with affordable pricing, the VKA is a viable alternative to the VKG and VKM series of flow metering products, particularly for OEM applications where conventional meters either fall short on pressure ratings or require costly materials.
How Viscosity Compensation Works
The VKA employs a spring-loaded float with an integral orifice to maintain consistent accuracy even as oil temperature causes viscosity to shift during operation. According to specifications, the meter is calibrated at a viscosity of 105 cSt and holds ±4% FS accuracy there; viscosity shifts anywhere within the compensated range add no more than another ±4% FS.
Designed for Industrial Oil Service
The VKA is designed for hydraulic oil flow monitoring in injection molding machines, lubricating oil measurement in paper mills and industrial gearboxes, and gear oil tracking in industrial drive systems. Common uses also include lubrication circuits, pulp and paper, hydraulics, extraction machines, and printing machines.
Wetted materials suit continuous oil service: a nickel-plated brass housing and fittings, brass float, 301 stainless steel orifice and spring, ceramic-oxide magnet, and NBR seal. The meter handles media temperatures from -13°F to 212°F (-25°C to 100°C) and ambient temperatures from -13°F to 167°F (-25°C to 75°C).
Installation Flexibility and Control System Integration
Connections are 1/2" NPT as standard, with 3/4" NPT available as an option. Switch-only versions mount in any flow direction, while meter versions install vertical-up or horizontal, with the horizontal direction specified at ordering. Changing position never requires recalibration, and flow must always follow the direction of the arrow on the body.
For control system integration, switch-equipped versions carry a reed contact that provides a simple limit signal for PLCs, alarms, or interlocks, with the switch point set by the user directly on the instrument. Wiring is through a plug-style DIN connector, and a conduit fitting option supports hard-piped electrical installations.
Specify Flow Direction When Ordering
Certain models require a flow direction at the time of order: vertical bottom to top, vertical top to bottom, horizontal left to right, or horizontal right to left, indicated as directly facing the flowmeter. Orders without this specification cannot be processed, so include the direction with your model number or contact our engineers for help determining it.
Made in USA and BABA Compliant
The VKA is made in the USA, manufactured in Pittsburgh, PA, with BABA (Build America, Buy America) compliant models available to support federal infrastructure project requirements. US manufacturing also supports rapid availability. Due to the ongoing implementation of EU Directive 2020/2184, which restricts brass materials, product availability is subject to change at any time as production transitions to US facilities.
Common Questions about VKA - Viscosity-Compensated Flow Meter
Flow lifts a spring-loaded float against an orifice inside a cylindrical measuring tube, and a magnetically coupled pointer on the side of the body indicates the reading. In switch versions, the float's magnet actuates an adjustable reed contact for monitoring. This float principle keeps readings compensated across 30 to 540 cSt.
Eight oil flow ranges are offered: 2...6.3 GPH and 6...20 GPH, then 0.3...0.9, 0.6...1.6, 1.5...4.2, 3.0...8.5, 6...15, and 8...26 GPM. Every range comes as switch only (VKA-51xx), meter only (VKA-61xx), or meter and switch (VKA-71xx) model numbers, with option suffixes added to the order number.
Base accuracy is ±4% of full scale at the 105 cSt calibration viscosity. Viscosity changes within 30...540 cSt cause additional deviation of at most ±4% of full scale, and repeatability is ≤1%. The scale stays valid across that range, so readings remain usable as oil warms and thins in service.
Maximum operating pressure is 3,600 PSIG, and pressure loss reaches 8 PSI at full flow. Media temperature limits are -13...212°F (-25...100°C), with ambient limits of -13...167°F (-25...75°C). The flow range may be exceeded by a large margin with non-pulsating flow, though maximum operating pressure must never be exceeded.
No. The instrument scale is suitable for the entire 30 to 540 cSt viscosity range without recalibration, and none is needed after a change in mounting position either. Media should be clean and homogeneous; viscosities above the compensated range will produce large deviations in the measured values.
Switch versions use a normally open reed contact, adjustable over the full measuring range; suffix ..U substitutes an SPDT changeover contact. Ratings are max. 230 VDC/0.26 A/60 W and max. 240 VAC/0.42 A/100 W, cCSAus approved. The DIN 43 650 electrical connection carries IP65 protection, and the side indicator is IP54.
Standard fittings are 1/2" NPT threads on a nickel-plated brass body. Adding suffix ..B to the order number specifies 3/4" NPT connection fittings, and suffix ..C adds a 1/2" NPT conduit fitting for the electrical connector, useful where local codes call for conduit wiring.
Yes. The VKA is built at KOBOLD's Pittsburgh, PA facility, and models meeting Build America, Buy America (BABA) domestic-content rules can be supplied for federally funded infrastructure work. Domestic production also supports quick delivery on standard configurations, and brass meter production continues to move onshore.
For clean media, VKA models are almost maintenance-free. Where calcium or dirt deposits form in the housing or on internal parts, clean the instrument regularly, taking care not to damage the sensitive orifice. Large dirt particles, or ferritic particles drawn to the magnetic float, can cause blockage or false alarms.
Product Specifications
Measuring Ranges
2...6.3 GPH to 8...26 GPM
Fittings
1/2" or 3/4" NPT Threads
Viscosity Range
30-540 cSt
Temperature Range
-13...212 °F (100 °C)
Accuracy
± 4% FS (Add ± 4% for Viscosity Changes)
Product Features
Switch Only, Meter Only, or Meter/Switch Versions
Certifications/Approvals: cCSAus
Sample Applications: Lubrication Circuits, Pulp and Paper, Hydraulics, Extraction Machines, and Printing Machines
BABA (Build America, Buy America) compliant models available
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