RFID non-contact technology: Checking pre-charge pressure on bladder and diaphragm accumulators

New connection adaptors enable the use of innovative sensors to check hydro-pneumatic accumulators without having to manually work on them.

The new SBAA and SDAA types of accumulator adaptors from STAUFF enable the non-contact checking of the accumulator pre-charge pressure of hydro-pneumatic bladder and diaphragm accumulators using STAUFF’s PT-RF pressure transmitter and a corresponding reader – for an easy, fast response measurement without any loss of pressure.

On new installations the existing gas valve fitted to the accumulator is first removed and then the adaptor is simply screwed onto the gas filler connection on the accumulator.

A PT-RF pressure transmitter is permanently attached on the side of the adaptor which is also supplied with a gas valve to allow the accumulator to be pre-charged as normal. A range of gas valves to suit most bladder type accumulators fitted with a 7/8” UNF bladder connection and diaphragm accumulators fitted with the M28 x 1.5 connection are also available from STAUFF.

For retrofitting existing systems, prior to the adaptor and sensor being fitted to the accumulator, the pre-charge pressure first needs to be released and the existing accumulator gas valve removed.

Depending on the system requirement, PT-RF series pressure transmitters are capable of recording measuring ranges of between 0–16 bar and 0–600 bar (relative), with a high accuracy reading of  ±0.5 per cent based on the respective full scale common in hydraulics systems. The functional principle of the transmitters is based on innovative RFID technology, the energy required for a measurement is transferred wirelessly to the pressure transmitter via the antenna of the associated reader and display device so that the transmitter requires no internal or external power supply and no wired connectivity, making it a versatile digital pressure measurement system for any hydraulic system. The transmitters are suitable for measurement of both gas and hydraulic systems.

Simply by pressing a button, the pressure transmitter is activated; a current measured value is determined within only 0.5 seconds and then immediately transmitted back to the hand-held reader and display device — the illuminated display providing a visual display and stored for further evaluation. In addition to the pressure value itself, other relevant information is also transmitted including measurement in real-time, date and the unique serial number of the pressure transmitter installed which enables the clear assignment of the measuring point – a basic prerequisite for end-to-end documenting of test results. Over 15,000 measurement data sets can be stored in the integrated memory of the reader. The software included in the scope of delivery enables subsequent evaluation and further processing of the measured results previously transmitted to a PC or laptop via USB interface. From within the software the serial number of each transmitter can be given a unique name, as wells as a specific target pressure can be set including a +/- tolerance.

For standard pressure measurement the software includes several standard pre-defined excel templates or the ability to create your own. Once defined a report can then be selected from within the PT-RF software, which then automatically imports the selected stored data into the excel report for the transmitter selected.

For pre-charging the software includes a pre-charge monitoring template. In order to use this function the minimum hydraulic system pressure is added to the selected sensor naming function in the software. The pre-charge tolerance +/- per cent can then also be added. Once a measurement point is selected from the software and the report function selected, the information is automatically imported into the report. The report then indicates the actual pre-charge pressure versus temperature recorded and compares it to the target pre-charge pressure at that given temperature. The report makes adjustments for change in temperature and highlights if the pre-charge pressure is within the accepted tolerance range.

The benefits of using this innovative technology, extends not only for non-contact measurement of pressure in hydraulic systems but also for hydraulic accumulators, allowing operators, maintenance personnel and repair technicians the capability to carry out multi-point measurement without any extensive training and within a few seconds – by simply a press-of-a-button, and then documented in a reliable and accurate process.

The use of the PT-RF in testing pre-charge pressure on Hydraulic Accumulators is safe and reliable without the need to unscrew and re-install pressure gauges, other contact type measuring and display devices, which effectively mean a temporary opening of the system that can lead to the loss of accumulator pressure resulting in impaired performance.

The PT-RF system is available as a set encompassing the hand-held reader, transmitters and software or supplied separate i.e. reader only. Multiple readers can be used on large plants to facilitate remote measuring.

STAUFF has been developing, producing and marketing hydraulic fluid components and accessories for over 50 years, with the manufacturing and design headquartered in Germany and products distributed in more than 40 countries through a global network.

Having been present in Australia for over four decades, STAUFF has branches in Adelaide, Brisbane, Melbourne, Sydney and Wollongong. The company’s sales and distribution offices are also supported through a national network of authorised distributors and stockists.

STAUFF’s products provide port-to-port solutions, from the component level, filter systems and filter elements for fluid media, pressure and flow test systems, hydraulic accessories, hydraulic accumulators, flanges, tube connectors and quick release couplings, clamping systems for pipes, hoses and cables, machined parts through to value-adding services.

While manufacturing and design are carried out in Germany, we also offer value-added services in Australia. So if you buy components such as tubes and clamps from us, we offer value-added services such as assembling the parts, bending tubes, forming and custom system-build solutions.

STAUFF facilities and products are covered by Quality and Performance approvals from Lloyd’s Register QA, SAI Global, Bureau Veritas, DNV GL.

For information about the PT-RF system contact STAUFF or visit www.stauff.com.