Variable Area Flow Meters

• Port Sizes: 1/4” - 1.5” and 3”• Measure: Oil, Water, Air• Accuracy: ±2% of full scale• Repeatability: ±1%• Other specifications:

• Flow ranges: 0.02 - 300 GPM (0.1 - 1100 LPM)• Construction: Aluminum, brass and T303 stainless • Connections: SAE, NPTF, BSPP, Code 61/62 flange• Pressure up to 6,000 psi (414 bar) maximum• Temperature up to 240 °F (116 °C) • High Temp units to 400 °F (204 °C)

Variable Area Flow Meters

General Design Features• Operates in any position• Easier to read linear scale• 360° Rotatable guard/scale• No flow straighteners or special

piping required• Reverse flow bypass option• Good viscosity stability to (400 SUS / 90 cSt)

Effects of Viscosity • Hedland’s sharp-edged orifice ensures operating stability and accuracy over a wide

viscosity range.

Effects of Viscosity

Effects of Density

31.151.

876.

Corrections for more or less dense fluids can be made to

standard scales using the following correction factor:

√ 1.0 / specific gravity, water/water-based meters

√ 0.876 / specific gravity, petroleum-based meters

Example: Measuring liquid propane with petroleum meter• Fluid ~ Liquid Propane (LPG)• Scale Measured Flow ~ 25 gpm

1. Select (LPG) specific gravity from the Fluid Selection

Chart = 0.51

2. Since petroleum meter is utilized, select petroleum formula

3. Multiply scale reading by 1.31, 25*1.31= 32.75 (actual flow of liquid propane)

Pneumatic Flow Meters• Multi-pressure scale • Single-pressure scale

Pneumatic Flow Meters

• Compressibility of Gases• Significant• Density varies with

• Pressure• Temperature

• Effects of Specific Gravity• Any changes from standard has

a proportional effect on meter accuracy

Pneumatic Flow Meters• Example: Measuring Natural Gas with a Air meter

• Line Pressure =140 psig• Temperature = 40° F• Fluid = Natural Gas 0.6 SG

• Pressure correction:

• Temperature:

• Specific Gravity:

• Total correction factor :

861.7.14

7.1141

140f

971.530

4602

40f

775.3 0.6f

648.775.*971.*861. totalf

Pneumatic Flow Meters

• To determine actual flow vs. indicated flow

• To determine which standard meter is required to achieve a flow of 85scfm

scfmfflowscfm total 1.55)(648.*)(max85

scfmf

indicatedscfmactualscfm

total

6.38)(648.

)(25)(

Pneumatic Flow MetersTo determine which standard meter is required to achieve a desired flow of 85 scfm

• H671A-050• H771A-050

Actual scale range

)(1.77)(648.)(max50 actualcfmfflowscfm total

)(7.7)(648.)(min5 actualcfmfflowscfm total

scfmfflowscfm total 1.55)(648.*)(max85

Flow-Alert® Flow Switches

Available in single or double switch• Reed

• SPST-N.O. 10W, 50V and .5 A max• SPST-N.C. 5W, 50V and .5 A max• Changes state when internal magnet is in

proximity - returns to original condition when magnet moves away

• Micro• 220 VAC @ 10A and 125VDC @ .5A• Single(1) or Double(2) prewired single-pole, double-

throw (SPDT)

MR Flow Transmitter• Output options and Power requirement

• 0-5V Output requires 10-30Vdc@.75W max• 0-10V Output requires 12-30Vdc@.75W max• 4-20mA Output loop powered 30Vdc max

• Digital rate and total flow indication• Operates as part of a totally integrated electronic

process control/ data acquisition system• Non-contact sensor electronics • In-field compensation for specific gravity and viscosity • Rating: NEMA 12 and 13 (IP 52/54)

Applications• Agriculture

• Irrigation systems• Pesticides and Ag Chemicals• Coolant Flow on Thermal Transfer Equipment

• Telecom• Coolant Flow on Calorimeters

• Automotive• Case Drain – Hydraulic Power Units• Engine Coolant Test Systems• Transmission Flush Systems

• Compressed Air Systems

Applications• General Manufacturing

• Monitor air compressor output• Monitor air supply to balance systems

• Semicon• Coolant Flows• Flush Flows

• Fluid Power• Case Drain – Hydraulic Power Units

Thank You

+44 (0)1280 817304 sales@bellflowsystems.co.uk www.bellflowsystems.co.uk