The days of open abrasive blasting, with minimally trained operators using loads of cheap abrasive are dwindling in the United States. Environmental, safety, and health regulations, combined with demanding surface profile requirements, mean that abrasive blasting is often being performed in containment by skilled operators using higher priced media.
As contractors work to control their costs in this new work environment, they need to find ways to improve labor productivity. Carefully managing their abrasive consumption is one key to maximizing blasting productivity. Axxiom Manufacturing Inc. has introduced a new abrasive metering valve, a small piece of equipment designed to make a big difference in productivity.
Some contractors still believe that pushing as much abrasive as possible through the nozzle maximizes productivity. In reality, blasting with too much abrasive can actually lower productivity.
As the amount of abrasive in the airflow is increased beyond an optimal point, the exit velocity of the particles at the nozzle is drastically reduced, decreasing the amount of energy impacting the surface.
Once that begins to happen, production rates decrease and abrasive is wasted. Avoiding this problem by not feeding enough abrasives or “running lean” does not fully utilize the capabilities of the abrasive and blasting system.
Experienced operators can “tune” the abrasive mix by observing the quality of the surface cleaning and getting a feel for the cleaning rate as the abrasive flow is adjusted with conventional abrasive metering valves. However, this process can be time-consuming and difficult to replicate, even more so for less experienced operators.
To take out some of the time, guesswork, and waste out of metering abrasive to optimize its flow rate, Axxiom has introduces a new abrasive control valve, the MV2™ (patent pending) into its Schmidt® air blast product line. The MV2™, successor to the Schmidt® Microvalve, includes a new virtual position indicator (VPI). The VPI is an external indicator that accurately displays the position of the plunger relative to the abrasive orifice inside the valve.
Additionally, graduations show the number of turns the metering knob has been adjusted. This gives the operator more precision and consistency when adjusting the abrasive flow for different application conditions, nozzle sizes, blast pressures, and abrasive size and types.
The improved design of the MV2™ has other benefits. The valve also utilizes the compressed air before it is mixed with abrasive (the motive blast air) to loosen or aerate (or “fluff”) the abrasive particles sitting above the valve, where they tend to pack if stagnate for a while. loosening the packed media produces a more consistent flow of abrasive.
For a longer life of the valve, the internal components are made from improved abrasive-resistant materials. Because of its reconfigured body and fewer wearing parts, the valve is easier to disassemble and rebuild than its predecessor, resulting in parts and labor cost savings in the field.