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HSPV
Variable Area
information
- Introduction
A Variable Area (VA) Flowmeter, often referred to as a rotameter, is a reliable and cost-effective instrument used to measure the flow rate of liquids and gases by utilizing a float inside a tapered tube. As fluid flows upward through the vertical tube, it exerts a force on the float, causing it to rise until the upward pressure and buoyancy are exactly balanced by the float’s weight. The “variable area” refers to the increasing annular space between the float and the tube wall as the float moves higher, which allows for a direct visual or electronic reading of the flow rate based on the float’s position. This purely mechanical principle ensures high repeatability and requires no external power for basic visual models, making it an essential tool for industrial processes requiring simple, real-time monitoring.
- Working Principles
A Variable Area (VA) Flowmeter operates on the principle of maintaining a constant pressure drop while allowing the flow area to change in response to the fluid velocity. It consists of a tapered tube and a float that is free to move vertically; as fluid enters the bottom of the tube and travels upward, it exerts a dynamic force on the float, causing it to rise. The float settles at a height where the upward forces of buoyancy and fluid tension exactly balance the downward force of gravity (the float’s weight). Because the tube is tapered, the “annular area” between the float and the tube wall increases as the float rises, allowing more fluid to pass through until equilibrium is reached. This position corresponds to a specific flow rate, which can be read against a calibrated scale on the tube or transmitted via magnetic coupling in high-pressure metal-tube versions.
- Applications
Variable area flowmeters are prized across various industries for their simplicity and “fail-safe” nature.
Chemical & Pharmaceutical Processing
Water & Wastewater Treatment
Oil & Gas Industry
Food & Beverage Production
HVAC & Cooling Systems
Power Generation
General Manufacturing
Short Tube VA Flowmeter SGK
In stock
SKU:
SGK 1-3
The SGK 1 - 3 flow meters are based on the variable area float principle. They consist of a combination of borosilicate glass measuring cone and float, with a flow scale specific to the process fluid and calibrated to customer requirements.
download pdf datasheet
VA Flowmeter RA60/FA60 protective steel tube
In stock
SKU:
RA60/FA60
VA Flow Meter with protective steel tube and borosilicate measuring cone
The measuring units RA 60 and FA 60 are based on the variable area float principle.
In pipelines the RA 60 is installed by means of pipe unions and the FA 60 is mounted between flanges. The borosilicate glass measuring cone is located inside a protective steel tube with an inspection window.
VA flow meters RA 60 and FA 60 are most suitable for the flow measurement of transparent fluids and gases. Each unit is customized with a scale specific for the medium to be measured. RA 60 and FA 60 are used e.g. in plant and process engineering.
By installation of electrical limit value switches, which are adjustable throughout the entire measuring range, this devices can be used as detectors.
download pdf datasheet
VA Flowmeter RA65/FA65 protective steel tube
In stock
SKU:
RA65/FA65
VA Flow Meter with protective steel tube and borosilicate measuring cone
The measuring units RA 65 and FA 65 are based on the variable area float principle.
In pipelines the RA 65 is installed by means of pipe unions and the FA 65 is mounted between flanges. The borosilicate glass measuring cone is located inside a protection steel tube with an inspection window.
VA flow meters RA 65 and FA 65 are most suitable for the flow measurement of transparent fluids and gases. Each unit is customized with a scale specific for the medium to be measured. RA 65 and FA 65 are used e.g. in plant and process engineering.
By installation of electrical limit value switches, which are adjustable throughout the entire measuring range, this devices can be used as detectors. By installing an linear displacement sensor an output signal can be generated which is proportional to the height setting of the flow meter.
download pdf datasheet
VA Flowmeter RA77/FA77 plastic tube – glass cone
In stock
SKU:
RA77/FA77
VA Flowmeter with plastic armature and borosilicate glass measuring cone
Measuring units RA 77 and FA 77 are based on the variable area float principle.
The flow meter consist of a PVC armature with a measuring cone made of borosilicate glass. With these design features the RA 77 / FA 77 devices combine the advantages of the classical VA flow meters with those of pure plastic measuring devices: Cost-effective, resistant against almost all aggressive media, as well as a high accuracy of the measuring glass, which can be calibrated to suit any requirement. Especially with water and aggressive media this design has proven itself. Therefore the RA 77 / FA 77 are frequently used in the chemical industry and in water treatment plants.
By installation of electrical limit value switches, which are adjustable throughout the entire measuring range, this devices can be used as detectors.
download pdf datasheet
VA Flowmeter RA87/FA87 stainless steel tube
In stock
SKU:
RA87/FA87
VA Flowmeter with armature completely made of stainless steel
Measuring units RA 87 and FA 87 are based on the variable area float principle.
In pipelines the RA 87 is installed by means of pipe unions and the FA 87 is mounted between flanges. The borosilicate glass measuring cone is located inside a protective stainless steel tube with an inspection window. All parts in contact with the measured medium are made of stainless steel 1.4571.
VA flow meters RA 87 and FA 87 are most suitable for the flow measurement of transparent liquids and gases. Each unit is customized with a scale specific for the medium to be measured. RA 87 and FA 87 are mainly used in the chemical industry, in water treatment plants, in the food industry, and in other plant engineering applications.
By installation of electrical limit value switches, which are adjustable throughout the entire measuring range, this devices can be used as detectors. By installing an linear displacement sensor an output signal can be generated which is proportional to the height setting of the flow meter.
download pdf datasheet
VA Flowmeter SGA NBR lining
In stock
SKU:
SGA
VA Flow Meter with NBR-lining for acids, alkaline solutions and aggressive gases
The measuring unit SGA is based on the variable area float principle.
Wherever a robust and reliable device for the indication of momentary values and the monitoring of flows in pipelines is required in plant engineering, the SGA is the right choice as a reliable unit for the measurement of liquids and gases. This flow meter is available in a variety of cast iron versions for the application with various media and pressures.
The measuring range for H2O is 0.012 - 0.12 m3/h to 12 - 120 m3/h, the measuring range for gas is 0.15 - 1.5 to 100 - 1000 m3/h air at STP. Each unit is calibrated to meet the requirements of the respective customer and is fitted with a scale specific for the media to be measured.
download pdf datasheet
VA Flowmeter SGM
In stock
SKU:
SGM VA
VA Flow Meter for high temperature & pressure, chemical applications
In all cases where a dependable device is required for indicating instantaneous values and monitoring the flow in pipelines, the SGM is the obvious choice as a reliable device for measuring the flow of liquids and gases. Since the vertical position of the float is transmitted magnetically to a dial gauge, the SGM, as opposed to standard type variable area flow meters with a glass tube, is also suitable for measuring the flow of opaque media. Each device is individually calibrated to meet customer specifics and fitted with a medium specific scale.
download pdf datasheet
VA Flowmeter SGM PP/PVC
In stock
SKU:
SGM VA PP/PVC
The SGM PP/PVC VA Flow meter is a cost effective fully plastic Version - for chemical applications with highly acidic media, e.g. hydrochloric acid. Since the vertical position of the float is transmitted magnetically to a dial gauge, the SGM, as opposed to standard type variable area flow meters with a glass tube, is also suitable for measuring the flow of opaque media. Each device is individually calibrated to meet customer specifics and fitted with a medium specific scale.
download pdf datasheet
VA Flowmeter SKT/SKT/SKPVC plastic cone
In stock
SKU:
SKT/SKT/SKPVC
Plastic Cone VA Flow Meter for cost effective Measurement
The plastic flow meters SKT, SKP and SKPVC are based on the variable area float principle. The flowrate is indicated on a scale printed on the measuring tube by the indicator edge of the float. The indicator edge is identical with the largest diameter of the float. The standard scale has been designed in l/h and in % for the medium water (20 °C) and has two adjustable nominal value indications. Special scales for other substances are available on request.
download pdf datasheet
