Coincidently, two radically different “knife” gate valves appeared sixty years ago. These two very different designs added to the existing three styles of knife gates, and offered isolation options in a wider array of applications. One was what is now known as a Push-Through Knife Gate, and the other as a Guided Shear Gate (GSG).
Generation I of the original GSG was designed for PN16 (240-psig) and lighter applications and offered bi-directionally tight (zero leakage) isolation in slurries. The author became familiar with this valve when Gen II was brought to Canada and the USA in 1966. It was known as Josam-Wey, made at the Josam foundry in Michigan City, Indiana, USA.
Unbeknownst to most people at the time, the valve bodies were machined at Delta Machining Inc (DMI) in Niles, Michigan, USA. When Josam suffered financial trouble in the mid 1980’s and went bankrupt, Delta Machining approached the original patent holders and persuaded them to allow DMI to produce the valve and Gen III was born.
A significant market arose in the mid 1990’s and the need for large diameter high pressure slurry knife gates pushed DMI to spin off a subsidiary entirely consisting of the manufacturer of the highest performance knife gates. This subsidiary was called Delta Industrial Valves (DIV), and they designed Gen IV of the GSG, which pushed the pressure range past PN50 (Class 300) into PN100 (Class 600).
In 2015, DIV was sold to a large multinational pump company. This created a vacuum in the manufacturing abilities in Niles, Michigan and an opportunity presented itself to push the design even further under a new team. DSS Valves (www.dssvalves.com) was born and created Gen V using the DNA for the past three generations as the foundation of the valve, while introducing significant improvements. Today DSS produces the world’s highest performance knife gates up through PN250 (Class 1500) in both isolation and control versions. And curiously, of the five distinct styles of knife gate valves, is the only one that actually cuts, so really is the only “true” knife gate.
This ability to cut (or shear) has given the valve its tremendous success in mining and mineral processing in two main areas: highly abrasive slurries like concentrates and tailings, and pregnant leach solutions found throughout hydrometallurgical operations. The author has supplied more than 50,000 of these GSGs throughout the mining and mineral processing world, as well as into Pulp & Paper, Power, Chemical, Food, and Wastewater.
While there is no “perfect” valve, DSS’ GSG comes close. And the new care and attention to ESG (Environmental, Social, and Governance) goals makes GSGs so much more attractive as stewards of the process.
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