Clamp On Gas Flowmeters

Although industrial gas flow meters are widely utilised for liquid and water applications, it has long been accepted that this technology could not be applied to mass gas flow measurement primarily due to fundamental theoretical measurement limits. In fact only 4.9 x10–7 percent of the transmitted sound energy is received by traditional ultrasonic transducers. However, recent advances in gas flow mesaurement technology and processing have meant that despite lower acoustic impedance levels and higher attenuation levels in most gases, a clamp on gas flow meter can now measure transit times in gases where signal-to-noise ratios are extremely low. However, it is now possible to measure natural gas, steam, compressed air, hydrogen and air using clamp on flow meters.

Some of the gas flow meters available from RS Hydro:

Panametrics PT878GC

The Panametrics PT878GC clamp-on ultrasonic gas flow meter is a portable flow meter used to measure natural gas, compressed air, inert gas or any compressed gas application. The PT878GC can not only measure gas flow rates, but can also record and log data internally and then download it to a PC.

DigitalFlow CTF878

The DigitalFlow CTF878 clamp-on gas flowmeter utilizes a new technology called correlation tag (patented) to determine gas flow rates even at low pressure. The DigitalFlow CTF878 can measure a wide range of velocities in small to large pipes up to 150 ft/s (46 m/s), giving it broad applicability in gas flow measurement. It is used on plastic and metal pipes from 6 to 30 in (150 to 750 mm) in diameter. Accuracy is excellent?better than ?2 percent of reading?with repeatability of ?0.6 percent of reading. The turndown ratio is 43-to-1. This technology can measuredry air, oxygen, nitrogen, argon and natural gas at low pressure (<1bar a).

Panametrics GC868

The GC868 uses ultrasonic technology to enable measurement of a wide variety of gases, including those that are erosive, corrosive or sterile.

A clamp on ultrasonic gas flow meter produces signals that are five to ten times more powerful than those of traditional ultrasonic transducers. The new transducers produce clean, coded signals with very minimal background noise. The result is that a clamp on gas flow meter can now provide optimum performance even with low-density gas applications. Today, our ultrasonic clamp-on gas flowmeters can undertake steam flow measurement, compressed air and gas flow measurement, measure the flow of any gas including nitrogen, oxygen and natural gas and can then calculate mass flow using a pressure transmitter connected to the analogue input. Such clamp on flowmeters are extremely useful for measuring corrosive, errosive, toxic, high purity or sterile gases where it is not possible to install 'wet transducers.'

Examples include:

• air
• hydrogen
• natural gas
• fuel gases
• compressed air
• steam

As there are no modifications to the pipe, installation costs are dramatically reduced. Indeed, one instrument can be used to survey many flow measurement points in one day. The meter can be installed on any unlined pipe of metal or plastic construction from 0.75-24.0 inches in diameter with operating temperatures of -40° to 300° F.

For more product information, or information about panametrics flow meters, please use our instrumentation section.