VA 500 - Flow meter for compressed air and gases
RS 485 interface, Modbus RTU, 4...20 mA analogue output for m³/h, Pulse output for m³.
Details
Why measuring compressed air flow pays off
Compressed air submetering shows how much air individual machines, departments or production lines use and how compressed air consumption is distributed over the day. Costs can then be allocated internally by consumption and used as a KPI in ISO 50001 energy management or in a plant energy assessment. The baseline after the end of a shift points to leaks and permanent consumers; measurements before and after a measure show what it achieved. Load profiles with peak and base load are also the data basis for sizing piping, dryers and compressors. Because it measures from outside, the VC 600 makes this consumption measurement possible on existing piping without any intervention in the pipe.
How clamp-on ultrasonic measurement works on compressed air and gas
The VC 600 is an ultrasonic flow meter working on the transit-time (time-of-flight) principle. Clamp-on means the sensor measures from outside the pipe – non-invasively, also called non-intrusive. Two piezo transducers in the measuring unit send ultrasonic signals through the pipe wall, alternately with and against the flow. The transit-time difference gives the flow velocity; velocity and pipe cross-section give the volume flow. The difficulty with gases: they conduct sound far worse than water, so only a small part of the acoustic energy passes through the pipe wall into the gas. The measuring unit of the VC 600 is therefore tuned to the wall thickness of the pipe so that enough signal arrives even at low pressure; from 44 psig (3 bar(g)) the instrument measures reliably in metal pipe. Structure-borne noise traveling in the pipe wall is absorbed by the damping mat in the quick-release clamping system.
Mounting with half-shells and quick-release fasteners, without touching the pipe
The quick-release clamping system in 316L stainless steel (1.4404) consists of two half-shells with an integrated damping mat. It is placed around the pipe at a paint-free spot and closed with the four quick-release fasteners, alternating sides; the fasteners pull the half-shells evenly onto the pipe so that the transducers couple in with full contact. The measuring unit is then set on top and secured with two M4 screws. No ultrasonic gel or coupling pads are required, the spacing between the transducers is fixed by the measuring unit, and nothing more than a screwdriver is needed. Mounting location and straight pipe runs are part of choosing the measuring point; the details are in the operating instructions.
Selecting the measuring unit and clamping system for ¾ to 3 in. pipe
The quick-release clamping system is chosen by the outside diameter of the pipe, in ten sizes covering 0.98 to 3.54 in. (25 to 90 mm) OD – every NPS size from ¾ to 3 in. has a matching clamping system. The measuring unit comes in two versions, tuned to wall thicknesses of 0.06 to 0.087 in. (1.5 to 2.2 mm) and of 0.087 to 0.197 in. (2.2 to 5.0 mm); both fit every size of clamping system. Anyone who wants to measure several pipe sizes therefore needs only additional clamping systems, not a second instrument. What counts is the outside diameter, not the nominal size: a 2-in. NPS steel pipe measures 2.375 in. (60.3 mm) outside, a 2-in. sanitary stainless tube 2.0 in. (50.8 mm), and aluminum piping systems are often specified by metric OD such as 50 or 63 mm. In the order code, only the clamping system therefore carries the pipe-size code.
Commissioning: calculating standard flow in the device
A setup wizard guides the user through entering inner diameter, wall thickness, pressure and temperature; pressure and temperature can be fixed values or come continuously from external sensors. Finally the wizard checks the signal quality and confirms it. The VC 600 converts to the selected reference conditions itself – ISO 1217 from the factory, i.e. 68 °F and 14.5 psia (20 °C, 1,000 mbar) – and totalizes consumption as a compressed air meter; via Bluetooth the CS SensorApp shows live values and trends.
Retrofitting flow measurement while the plant is running
Typical measuring points for a retrofit without shutdown are the supply line after the dryer, branches to individual buildings or cost centers, the feed line to a machine with conspicuous consumption and high-pressure lines after a booster; nitrogen consumption can be assigned to individual points of use in the same way. The line stays closed, and no new connection in contact with the medium is created. The readings go via the selected interface to a data logger such as the DS 500 or directly to the energy management system.
Frequently Asked Questions About Clamp-On Flow Measurement with the VC 600
| Feature | VC 600 |
| Measuring principle | ultrasonic transit-time difference, clamp-on |
| Measuring range | 0.26–66 ft/s (0.08–20 m/s, F1); 0.26–82 ft/s (0.08–25 m/s, F2) |
| Accuracy | ±1.5 % of reading ±0.3 % of full scale |
| Pipe outer diameter | 0.98–3.54 in. (25–90 mm), NPS ¾–3 in.; larger sizes on request |
| Wall thickness | 0.06–0.20 in. (1.5–5.0 mm): measuring unit B1 0.06–0.087 in. (1.5–2.2 mm), B2 0.087–0.197 in. (2.2–5.0 mm) |
| Pipe materials | steel, stainless steel, aluminum |
| Line pressure | from 44 psig (3 bar(g)); upper limit set by the pipe, not by the sensor; suitability for high-pressure lines assessed from pipe and operating data |
| Gases | compressed air, nitrogen; others on request |
| Calibration | factory calibration with certificate; standard via gas constant (D1), true gas calibration for the selected gas (D2); recalibration by sending in the measuring unit |
| Temperature | line −22 … +176 °F (−30 … +80 °C), ambient −4 … +158 °F (−20 … +70 °C) |
| Reference conditions | ISO 1217 (68 °F, 14.5 psia, dry = 20 °C, 1,000 mbar; the CAGI / Compressed Air Challenge standard conditions for SCFM), DIN 1343 normal conditions for Nm³ (32 °F, 14.7 psia = 0 °C, 1,013.25 mbar), 59 °F/14.2 psia (15 °C/981 mbar), 59 °F/14.7 psia (15 °C/1,013.25 mbar, gas-industry base to ISO 13443) |
| Inputs | pressure 4–20 mA or Modbus RTU (PTS 500); temperature Pt100/Pt1000 or 4–20 mA |
| Outputs per version | I1: 4–20 mA + RS 485 Modbus RTU · I2: 4–20 mA + IO-Link · I3: Ethernet with PoE, Modbus TCP + 4–20 mA + RS 485 · I4: M-Bus + 4–20 mA + RS 485 Modbus RTU; Bluetooth for the CS SensorApp |
| Display, memory | touchscreen; totalizer; data logger 50 MB (about 2 years at 10 min) |
| Supply, protection, location | 18–36 VDC, 7 W; IP 65; indoor use, not for hazardous (classified) locations |
Examples for compressed air at 7 bar(g) (≈ 100 psig) and 68 °F (20 °C), standard flow to ISO 1217 (14.5 psia, 68 °F), full scale at 66 ft/s (20 m/s). The complete table for every clamping system is in the data sheet.
| Inner diameter | Measuring range at 7 bar(g) |
| 0.85 in. (21.7 mm) | 0.50–125 SCFM (0.85–213 m³/h) |
| 1.65 in. (41.9 mm) | 1.87–467 SCFM (3.18–794 m³/h) |
| 1.97 in. (50.0 mm) | 2.66–665 SCFM (4.52–1,130 m³/h) |
| 2.37 in. (60.3 mm) | 3.87–968 SCFM (6.58–1,644 m³/h) |
| 3.19 in. (80.9 mm) | 6.97–1,742 SCFM (11.84–2,960 m³/h) |
A thermal sensor protrudes into the pipe and therefore requires a ball valve or a measuring section; the VC 600 is mounted on the outside of the pipe. It measures the flow velocity across the pipe cross-section and converts the data to standard volume using pressure and temperature; a thermal sensor measures the mass flow directly and must know the type of gas to do so.
Most clamp-on flow meters are designed for liquids. Gases conduct sound much less effectively, so a sensor unit is needed that can transmit a strong enough signal through the pipe wall. The VC 600 is designed for this purpose and measures flow in metal pipes starting at 3 bar(g).
The minimum pressure is 3 bar(g). The upper limit is not determined by the sensor but by the piping, since the device is mounted externally and is not subjected to pressure. Because the measuring range is specified in terms of actual flow velocity, the VC 600 measures high standard volume flows at high pressures: At 40 bar(g) and an inner diameter of 50 mm, a velocity of 20 m/s corresponds to approximately 5,800 m³/h, based on 20 °C and 1 bar absolute, using the ideal gas approximation.
In compressed air networks, a relative pressure sensor such as the PTS 500 or CS 16 is sufficient: The VC 600 converts a fixed air pressure value of 1,000 or 1,013.25 mbar to the absolute pressure required for standard volume calculations. A change in air pressure of 30 mbar alters the standard volume at 7 bar(g) by only about 0.4%. An absolute pressure sensor can also be connected and adjusted on the device.
Because the pipe wall determines how much sound reaches the gas. The sensor unit is calibrated for a specific wall thickness range to ensure that a sufficient signal is received even at low pressure. One version covers 1.5 to 2.2 mm, and the other covers 2.2 to 5.0 mm. Both fit all quick-clamping systems.
Some of the ultrasound waves travel further into the pipe wall and are reflected back at flanges, welds, and threaded connections. The damping mat in the quick clamp system absorbs this structure-borne noise at the sensor unit. If a flange is located close to the point of measurement or if the pipe is very rough, this can affect the signal. In such cases, damping clamps installed before and after the sensor—sized to fit the pipe and located no more than 50 mm from the quick clamp system—can help.
For steel, stainless steel, and aluminium pipes with an outside diameter of 25 to 90 mm and a wall thickness of 1.5 to 5.0 mm. Aluminium pipe systems for compressed air with diameters ranging from 25 to 80 mm fall within this range. The installation site should be free of paint, rust, and welds.
±1.5% of the measured value ±0.3% of the upper range value—the same value as for the VA 550 and VA 570 thermal sensors in their standard versions. This requires that the pipe data be entered correctly and that the point of measurement meet the installation requirements.
It displays this as the base load: Any current remaining at the end of the shift is attributable to leaks and continuous consumers. For very small residual volumes, we coordinate the measuring range and measurement uncertainty with you. The specific leak can then be located using the LD 500 leak detector or the LeakCam 600 acoustic camera.
Every VC 600 is calibrated on the CS INSTRUMENTS volume flow test bench before shipment and comes with a calibration certificate. For recalibration, only the sensor unit needs to be sent in; the quick clamp system remains attached to the pipe.
Product configurator
Please select from the options provided
[[ error ]]
[[ completedSteps ]] / [[ totalSteps ]]
-
[[ step.txt ]]
You have successfully completed your configuration.
Add it to your request now.
You have successfully completed your configuration.
Add it to your request now.
[[ 'Your product is %xx% % configured'.replace('%xx%', progressPercentage.toFixed(0)) ]]
Related products
VA 550 - Thermal mass flow sensor for flow measurement
Insertion sensor for demanding industrial applications, comes with ATEX + IECEx approval for Ex zones or DVGW approval for use in natural gas.
VA 520 - Thermal mass flow meter for flow measurement
for compressed air and gases. New digital electronics - improved accuracy.
VA 570 - Thermal mass flow meter for consumption measurement
ATEX + IECEx approval for Ex zones and DVGW approval for use in natural gas.
VA 526 – Compact flow sensor for compressed air and gases
Combines flow measurement, consumption monitoring, temperature measurement, and—optionally—pressure and humidity/dew point monitoring in a single sensor.
VD 500 – Flow meter for FAD measurement
For measuring immediately downstream of the compressor in moist air up to +180 °C
Accessories
Intelligent chart recorder DS 500 for compressed air and gases
Up to 12 optional sensors can be connected. 7" colour screen with touch panel.
PTS 500 - sensor for measuring of pressure and temperature
2 in 1 sensor, measures pressure and temperature processes
Standard pressure sensor CS 10 and CS 16
for measurements from 0...10 and 0...16 bar with accuracy of full scale max. 1% or max. 0,5%.
Digital pressure probe DPS 16
for measurements from 0...16 bar, RS485, G 1/2"
Thickness meter CS 0495
enables a quick, easy and accurate measurement of the wall thickness of pipes.
LeakCam 600 – All Relevant Leaks at a Glance
Detects multiple leakages simultaneously with globally unique Power Beam Forming. 4th generation technology - also suitable for other gases. Helps to locate and repair leaks - including cost estimation and ISO 50001 documentation.