The Editor

Motion Control

26 October 2009

Dear Sir,

May I draw your attention to the article 'BMG Hydraulics - the inside track' in your volume 11 No 3, 3rd quarter 2009 Motion Control Journal.

You were interviewing the managing director of BMG Hydraulics and asked him, “BMG is a SAFPA member and there are plans to introduce a hose assembly accreditation scheme. What are your thoughts on this?”

A part of the answer was the following “The fact that there are hose assemblers out there who do not perform 100% pressure testing on assemblies is a real concern. There is not a piece of equipment that leaves BMG Hydraulics premises without testing &”

The above statement reads to me that if BMG sells a pump it is tested before the customer receives it. The same is true for hoses and valves.

Let us look at the practicalities of testing hydraulic hoses. We believe that the hydraulic hose market in South Africa is around 900 000 metres per month. If the average length of a hose assembly is 1,5 m this means that there are approximately 600 000 hose assemblies manufactured per month. If we assume that an average test on a hose assembly takes at least 10 minutes, this equates to a total testing time 6 million minutes or 100 000 hours. Based on a 40 hour week this would represent some 48 years of testing. Dividing that workload across 20 machines would still take 2½ years.

All of the major hose assembly companies in South Africa have hose testing facilities and customers can ask for and will receive certification of a tested hose assembly, but to expect our industry to test every hose assembly is just not practical as seen from the calculation above. It is important that we do not create an unattainable expectation in the market.

David Michelle

Director

Genflex