Tokyo Keiso VC Series V-Cone Differential Pressure Flowmeter

V-cone differential pressure meter for short straight runs

The Tokyo Keiso VC series V-Cone flowmeter is a differential pressure meter in which a V-shaped cone sits in the centre of the line. The fluid is forced around the cone, its speed increases at the edge, and the static pressure falls. The upstream pressure and the pressure taken from the centre of the cone, measured at two tapping points, give the differential pressure that is converted to flow by the usual Bernoulli-based relation with a discharge coefficient.

Tokyo Keiso lists several benefits: a self-straightening flow profile, stable low-flow signals, no liquid retention, and straight-run requirements it quotes as less than one fifth of those for traditional orifice plates and vortex meters. The meter has no moving part, handles liquids, slurries, gases and steam, and is made from stainless steel.

Technical specifications

Data from the Tokyo Keiso VC series catalogue TG-F821-4E (dated February 2007; an older edition, so confirm current availability).

Straight-run and sizing rules

The catalogue tabulates the upstream and downstream straight length required behind a single 90 degree bend, two bends, a tee, butterfly or gate valves, expanders and reducers, separately for liquids, gases or steam at Reynolds number up to 200,000 and for gases or steam above that. Several fittings can sit directly upstream with zero straight run, and one more diameter is added when the beta ratio is 0.70 or more. The run is measured from the flange face of the meter.

The flow formula uses the beta ratio, pipe inside diameter, discharge coefficient, differential pressure, density and, for gas, the expansion factor, so sizing needs the fluid density, line pressure and expected flow range.

Ordering notes

The model code selects connection type and rating, material, connection size and beta ratio (two-digit codes 45 to 80). Non-standard specifications are possible on request. Please give the fluid and its condition, flow range and flange standard so that the beta ratio and the differential pressure range can be matched to your transmitter.

How the VC-VCONE Tokyo Keiso VC series works

The VC series is a differential pressure meter with a cone in the middle of the pipe. The flow must pass around the cone, so the speed rises at the edge and the static pressure falls. The meter takes the pressure upstream and the pressure at the centre of the cone, and the difference gives the flow rate. The cone also flattens the velocity profile, so the meter needs short straight pipe runs. The VC-VCONE has no moving parts.

Where the VC-VCONE is used

• Liquid, gas and steam lines
• Slurries and dirty process fluids
• Sites with little straight pipe
• Low flow rates where stable signals are needed
• Fuel, utility and process plant piping

Selection checklist for the VC-VCONE

• Line size from 15A to 400A
• Beta ratio from 0.45 to 0.80
• Material SS304 or SS316L
• Flange: JIS 10K, JIS 20K, ASME class 150 or 300
• Tapping connection of Rc1/2 or Rc1/4
• Fluid, temperature and pressure
• Flow range and Reynolds number of 8,000 or higher
• Differential pressure transmitter and manifold options

Installation, commissioning and maintenance notes for the VC-VCONE

Fit the meter between flanges with the high pressure tapping upstream and keep to the straight lengths in the catalogue. Connect the impulse lines to a differential pressure transmitter through a manifold, and fill the lines for a liquid or drain them for a gas. Set the transmitter range from the sizing sheet. Check the zero and the lines at planned intervals.

Requesting a quotation for the VC-VCONE

Please send the line size, the fluid, the flow range, the pressure, the temperature and the flange standard. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided. The catalogue on this page is an older edition, so availability is confirmed before an order.

VC-VCONE accuracy and turndown

The standard uncertainty of the discharge coefficient is 2.0 percent and the standard turndown is 10 to 1. The minimum differential pressure is 0.025 kPa for gas and liquid and 0.05 kPa for steam.

VC-VCONE face-to-face length

The length is 203 mm for 15A to 25A and rises to 762 mm for 300A to 400A. A 40A meter is 254 mm, a 100A meter is 406 mm and a 200A meter is 660 mm.

VC-VCONE pressure rating

Pressure and temperature follow the flange rating and the material. The reference table lists 1.4 MPa at 120 degrees C for JIS 10K and 3.4 MPa at 120 degrees C for JIS 20K.

VC-VCONE sizing records

Keep the sizing sheet, the beta ratio and the transmitter range with the instrument file.

Choosing the right VC-VCONE beta ratio

A smaller beta ratio gives a larger differential pressure at low flow, and a larger beta ratio keeps the pressure loss lower.

Documents and quotation

The Tokyo Keiso VC V-Cone catalogue is attached as a PDF. It is the 2007 edition, so we recommend confirming current availability and specification with the manufacturer through our RFQ process. Seven Star LLC is an independent supplier in Muscat; price and lead time are confirmed per enquiry. Related range: flowmeters and the ABB ProcessMaster FEP500 for liquid lines where a magnetic meter is preferred.