Specialist helps with novel plastic valve design

Designing and manufacturing a full featured yet low cost transfer systems for commodity chemicals and food products that are installed in plastic drums was the challenge presented to Micro Matic USA.

Designing and manufacturing a full featured yet low cost transfer systems for commodity chemicals and food products that are installed in plastic drums was the challenge presented to Micro Matic USA of Northridge, California.

Recognising the needs of the company's OEM customers, the plastic disposable valve was conceived with designed-in environmental and worker safety features.

Micro Matic undertook a five year developmental effort with the help of its moulding supplier Minnesota Rubber QMR Plastics to reshape how liquid chemicals are stored and dispensed.

"The idea began with a customer who wanted a plastic valve which would complement standard recyclable plastic containers", reported Henrik Rokkjaer, General Manager for Micro Matic.

"The plastic chemical drum industry is large with annual production estimated at 100 million containers".

"So the potential was substantial and we set out in 2000 to design a dispense system that would complement our stainless steel product line, add significant user and environment friendly features while keeping costs low".

"We believed the driver for product success would be price - the valve system had to have exemplary features and benefits".

"But we had to manufacture it at a cost acceptable to a very price sensitive commodity chemical industry".

"Introduced early this year, we call our new design the Economic Plastic Valve or EPV system".

Functionally, the EPV is three products in one.

First, the EPV valve replaces the age-old plug or "bung in the drum" screw-in device providing a higher level of packaging integrity during transit and storage.

Secondly, it's a completely closed system for dispensing liquid chemicals and reseals itself before disconnecting.

Thirdly, it's a security mechanism which prevents accidental spillage, product tampering and promotes worker safety.

Used in any of these three modes, the EPV's unique design safeguards against crosscontamination through a series of special seals and colour-coded key locks.

Moulded from high density polyethylene and completely recyclable, the EPV provides a versatile and comprehensive chemical resistant system.

Cost is low enough so you can dispose and recycle both drum and valve when the drum is empty.

Early on in the concept stage, Rokkjaer said the company began to involve its long term supplier of seals Minnesota Rubber QMR Plastics.

"Our goal was to develop a unique design which would be fully patented".

"We needed a supplier who we trusted that could help us through the design process".

"We had no prior experience with plastic products", stated Rokkjaer.

"However, Minnesota Rubber was an experienced custom rubber seal supplier we used for many years on our steel chemical handling products".

"That, plus they had a custom plastic moulding division with a successful track record manufacturing assemblies made of plastic and rubber".

"We brought them into the design picture confident of their capabilities".

Micro Matic began the design process using traditional methods for modelling prototypes and machining components out of polyethylene bar stock.

Components were screwed together, tested for function and reworked as needed until an acceptable operating prototype was arrived at that met its features/benefits criteria.

These prototypes took about a year to refine.

Once functional prototypes were ready, QMR Plastics created CAD models using its Ideas design software involving a series of design iterations for each of the components.

Stan Buisman, QMR Plastics programme development and design manager in charge of the EPV project, said the biggest challenge was to develop a really robust assembly design with a highly reliable sealing function that could handle all types of storage, long-term hard usage with most commodity chemicals and at a wide temperature range.

"The EPV valve system we arrived at is made up of two assemblies", reported Buisman.

"The valve (which also performs as the bung in a conventional drum) has three plastic injection moulded components and five rubber moulded seals".

"The coupler has six injection moulded components and five rubber moulded seals".

"A major design challenge was identifying the correct resin formulations for the parts, which were to be compatible with the two classes of elastomer formulations developed for the seals, an EPDM and a fluorocarbon series of formulations".

"The formulation series was necessitated to handle various chemicals which these valves would be used with".

The resins selected also needed to support design elements for welding and assembly of the plastic components as well as the tolerance requirements so groove paths and sealing surfaces were fail safe.

Throughout this two-year development process, the designs were targeted to exceed UN testing requirements which was done with preproduction quantities.

Like the age-old bung, the EPV valve assembly threads into the drum opening and performs the sealing function.

The coupler easily inserts into the top of the valve and is ready to do its job as a dispensing device to deliver the contents of the drum or container.

The coupler rotates 360 degrees so you can dispense in any direction.

The outlet port has a standard 1.25in long by 0.75in diameter threaded nozzle for easy connection to machinery such as commercial fertiliser applicators and food ingredient mixing systems.

A 1.5in-long spout at the bottom of the valve body has 0.75in diameter flanged edges to connect to a polyethylene dip tube reaching the drum bottom.

One of the great features of the EPV system is its very clever "lock and key" design which helps prevent accidental spills and guards against incorrect usage.

Using a series of 12 different colours which represent 12 different key profiles, the EPV valve will allow the user to differentiate a range of chemicals in similar containers thereby making them easy to identify correctly and easy to dispense.

For example, a red EPV valve will only connect with a red EPV coupler.

A blue valve matches up only with a blue coupler.

And so on.

All "keys", while different, operate on the same unique sealing principal to prevent cross contamination, unwanted worker exposure and environmentally hazardous spills.

According to Rokkjaer, the EPV system is fully patented with 18 different claims to its unique design.

"Product integrity prior to running production quantities culminated with independent (UN) United Nations Level II testing", reported Rokkjaer.

Using the EPV valves in 55 gallon plastic containers, a rigorous 28 day test cycle included cooling, heating, dropping the filled drums at different angles, stacking the drums three high, vibrating and shaking them and transporting them globally under these conditions over the 28 day period.

The testing certification ensured the valve's strength and sealing integrity and means the EPV system meets all required international shipping standards.

Buisman stated: "By partnering with our customer in a codesigning effort, we were able to help Micro Matic bring to market a truly new way to safeguard, transport and dispense commodity chemicals that is economical, operator and environmentally friendly".

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