Patented dispense valve designed for reliability

Colour and chemical dispensing has come a long way since the advent of the graduated container. Weighing scales of the mechanical dial type were replaced initially by load cells, and have now been superseded by digital scales. The first system of multi-product automatic dispensing was pioneered over 25 years ago by a Manchester-based company using analogue control logic (punch card recipe entry), load cells and pneumatically actuated, gravity fed valves.

Time and technology has moved on. Today, a computer engages directly in two-way communication with the dispense system and scale. Some material handling and on-line mixing adds further advantages. A typical system confers the capability to place empty containers at one end of the line and receive 60-120Kg drums of mixed colour with four to five components in two to three minutes per container. A useful development within the modern textile plant.

Yet, despite all the electronic wizardry, users still have trouble with dispense systems. Usually mechanical trouble.

"With any dispense system, the quality of the components is of prime importance," says Peter Hanmer of Ozark Systems, a designer and manufacturer of dispense systems. "Experience has shown that a number of problems which occur repeatedly with any dispense system can be directly attributed to the dispense valves. These problems include sticking valves and sluggish operation, causing lack of throughput speed and inaccurate and off-shade dispensing which, in turn, leads to colour corrections and an increase in wastage of both product and material."

Frustrated by this situation, Ozark Systems has taken the bold step of developing and patenting its own dispense valve in a bid to overcome many of the above problems. The patented valve's unique design is based on over 25 years' of experience. It is extremely accurate, allowing maximum throughput, requires minimum maintenance and is designed to provide many years of trouble-free operation, claim Ozark.

Its design and manufacturing quality may best be described as substantial. It looks and feels solid - fragile or lightweight it is not! Its stainless steel/co-polymer construction is impervious to rust and will not be degraded by any of the large number of chemicals found within the industry.

A multi-stage design, it incorporates a co-axial flow pattern which reduces the problems of spray and spatter, particularly with low viscosity liquids. Fail-safe operation means that the valve does not rely on keeping compressed air available during non-running periods to ensure that the valve remains tightly shut. The sealing arrangements are designed to ensure that the product does not leak back into the actuation mechanism.

In one instance during trials the valve was left for a period of three months with the product line connected and product inside. When the power was reconnected the valve functioned correctly and without problems, says Ozark.

A family of valves is available to cover all requirements, from sampling to production dispensing. Supply of material to the valves is controlled by suitably sized pumps which, together with high integrity scales and the lack of user-adjustable points on the valves, provide for a high quality component within the system. The pumps are controlled in a unique pattern to enable high speeds and accuracies to be achieved, says Ozark. A system of dual scales can be fitted to the system, allowing bulk weighing and sample dispensing to take place at the same point. Of course, once the product is weighed out, the container needs to be mixed, dependent on several factors. The type of mixer being important to the speed of throughput, Ozark also supplies a range of on-line mixer systems.

Immediate savings with an automated dispense system are achieved through reductions in manpower levels, raw material wastage, effluent costs and machine waiting time. Equally important, however, is reliability - how much downtime can the end user look forward to, and what is the cost of the annual maintenance contract? These factors are seldom taken into account when purchasing a system, says Ozark.

In respect of this last point, Ozark is underlining its confidence in the new valve by offering a two-year warranty.

The above article is reproduced here by kind permission of World Textile Publications Limited

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