TOTAL VALVE SOLUTIONS

The Art of Specifying in the Valve Industry

Like most industries, marketing experts try to distinguish their products from those of their competitors, by having certain features specified by consulting engineers, and end users. In most cases this is accepted practice, and of benefit to all, but the degree of specification “innovation” varies with the degree of competition in a particular market. One such market is that of air valves in South Africa.

This market was, for many years, dominated by a locally designed and manufactured product, until the patent rights of the product expired. Copies of this product soon appeared, turning this market into a fiercely contested “battlefield”. It seems that the South African water industry has been misled over the years, and on many fronts, about the merits of the original South African air valve. That original product had its “battle” against an Israeli manufacturer, which entered the fray in South Africa in the early 1990s. This international company is by far the largest manufacturer of air valves in the world, with some fantastic innovations, and “zero maintenance” required – ideally suited for African conditions.

Specifications for the South African market were written to keep the Israeli company out of contention, but the market soon realised the benefits of their product, and the adventurous users who tried it remain loyal customers. The Israeli company, A.R.I., formed a joint venture in South Africa in the 1990s, and have subsequently also started a program of local manufacture, proving its absolute commitment to the South African industry.

So, back to the strategy of writing specifications: the Marketing Manager of A.R.I. South Africa wrote a short article on one of the specifications, made by the local air valve marketers, which is innovation taken to a ludicrous level. Unbelievably, this specification still appears occasionally, and is, for some unaccountable reason, accepted by the otherwise highly regarded water engineering industry in South Africa. The article follows below.

Air Valve Specifications

It happens in all areas of business that sales and marketing people write specifications to give their own products an advantage over their opposition. When these specifications are technically correct and show legitimate advantages, this is excellent for that product, but very often claims are being made that are not technically correct, and sometimes they are downright intent on misleading the reader / designer and I am afraid these incidents happen more often than not.

Let us examine the following statement that was made back in the early nineties by a prominent valve manufacturer that is still in the market today.

SAFETY: The valve shall incorporate an over pressure relief feature comprising of assembly seals which are designed to fail at a predetermined critical pressure. This protects against possible damage to valve and pipeline, as well as against possible injury due to the explosive effect of suddenly released air.

In the analysis of the statement the following is very clear to me;

The elaborate wording of “over pressure relief feature comprising of assembly seals” describes what is simply known as gaskets. The valve design incorporates two gaskets that seals between a barrel (or a piece of pipe) and the end caps (two flanges), which are held together by means of tie-rods or long studs. These gaskets will fail at a pressure of around 90 Bar, which is the natural resistance of this type of gasket and is not “predetermined” at all. Further, as we all know, a gasket failure will cause a leak only, which in time will allow an over pressure to be neutralised. The key word being “time” as the longer it takes for the over pressure to be dispersed, the longer the over pressure exists in the valve / pipe. Apart from this, most pipes are designed for an operating pressure of 16 Bar or less – what protection does a gasket offer that fails at 90 Bar ?

It is also a fact that air is entrapped in an air valve that is closed – it may not be a lot of air, but it is present. Should a technician be working on the valve at a time when these gaskets fail, I fail to see what safety or protection it offers when air is exploded at a 90 Bar differential pressure!

In my humble opinion this is typically a case of trying to turn a weakness into a strength. But most surprisingly, as a result of “cut and paste” the feature still exists in specifications today!

Hannes Erasmus

ARI Flow Control Africa (Pty) Ltd

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