ASPRO

The ASPRO (Automatic Sensing Pressure Reversing Obturator) is a new concept that addresses the issue of back contamination from high-pressure carbon dioxide cylinders removing the opportunity for gas contamination. This is a particular problem in the food and beverage industry, where on numerous occasions’ contamination has occurred leading to product recalls and brand damage. There are also a growing number of applications in pharmaceutical production and clean process used in industrial production.
The ASPRO was developed for the prevention of back contamination of CO2 from a high-pressure cylinder, or dewer to the main flow stream, preventing back flow pressures up to 3600psi (250barg), in accordance with recommendations requested by EIGA and BCGA.

• The flow co-efficient (CV) allows full flow of media from filling stations and portable delivery systems therefore no delay in filling time.
• Fully automatic, no operator involvement required to operate the valve.
• Available in 2 sizes to suit most media, ¼ and ¾

Prior to the ASPRO being fitted, incidents of back contamination have occurred where the cylinder being filled has been used on toxic or other undesirable substances and has itself been contaminated over time. After filling, usually to about 1000 psi, the diverter is switched to re-cycle and due to the temperature being low in the cylinder, the pressure increases due to warming of the gas, back flow will then occur with possible leakage past the ball diverter.
Fitting the A.S.P.R.O prevents contamination of the storage vessel contents. This will automatically sense the backpressure and close a double check valve. The space between the two valves is then automatically vented to atmosphere, as a precaution against leakage past either valve.
Fitting a single check valve is not considered to be a suitable preventative measure when dealing with media that are used in the food and drink industries due to the possible leakage past this type of valve.
The European Industrial Gases Association (EIGA) has produced two related documents:

• Doc 68/99/EFD – Prevention of Carbon Dioxide Back-feed Contamination.
• Doc 70/99/EFD – Carbon Dioxide Source Certification.

The British Compressed Gases Association in the form of guidance note GN10 has dealt with implementation of these EIGA standards; this document provides a risk analysis matrix as follows: - 

Risk Category	Process characteristics	Preventive measures
0	Process at atmospheric pressure	None required
1	Tank pressure greater than process	Check Valve
2	Process pressure may rise above tank pressure under process fault conditions	Automatic shut-off valve operated by pressure differential
3	Process pressure is always greater than tank pressure	Double block and bleed valve operated automatically by pressure differential
4	Process flows return to tank	Separate delivery and process tanks connected with Double Block & Bleed
X	Vapour withdrawal system	Analysis of liquid samples at intervals

The Bestobell ASPRO is an automatic double block and bleed valve that meets the requirements of the BCGA GN10 up to risk category 4.
The majority of processes where this product is applied are in risk category 3 and a typical example is the process of cylinder filling, typical circuit as follows: - 

Fitting the ASPRO prevents possible contamination of the storage vessel and consequently prevents contamination or the delivery trailer.

The ASPRO automatically senses rising backpressure and closes a double check valve. As the double check valve closes the space between the two valves is automatically vented to atmosphere, any leakage past the closed valves is also vented to atmosphere thereby preventing the risk of back contamination.