Machine Design

Modified valves keep fuel additives in balance

An off-the-shelf valve head assembly was customized to work in a monoblock injector for fuel additives.

A valve stem was lengthened and bonnet threads redesigned to custom fit an injector monoblock.

Additives are put in fuel just before it goes into tankers and ratios must be precise. To keep the ratios in balance, engineers at Lubrizol Performance Systems in Atlanta developed a monoblock injector. It uses needle valves to provide precise flow regulation. They are inside the block itself, so there are no tube fittings, and therefore no leak paths.

Lubrizol initially manufactured the needle valve itself, then looked at costs and decided to outsource it. But they already had blocks produced. This meant that they needed a needle valve that could be threaded into their block and allow the stem to seat and operate properly. They turned to Parker Hannifin's Instrumentation Valve Division in Jacksonville, Ala., which modified an offthe-shelf valve head assembly by adding a special length stem and bonnet thread.

The resulting design lengthens the valve stem to match the depth of the block, while the bonnet threads match Lubrizol's. The result is a valve with a proven track record that fits into Lubrizol's existing design. The valve is rated to 10,000 psi and is currently in use in the petroleum industry.

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