System and method for controlling abrasive flow in a pneumatic blasting system

A method for automatically controlling abrasive flow in a pneumatic abrasive blast pot arrangement having at least one blast hose, the method including:

• providing a sensor for measuring abrasive flow rate through each of the at least one blast hose;
• providing an abrasive metering valve responsive to the sensor;
• providing a controller in communication with the sensor and the abrasive metering valve;
• inputting at least one predetermined optimum abrasive flow rate range having an upper limit and a lower limit, for a combination of nozzle size and abrasive type, into the controller;
• inputting a selected nozzle size and abrasive type combination into the controller, the controller being configured to determine an optimum abrasive flow rate range from the at least one predetermined optimum abrasive flow rate range based on the selected nozzle size and abrasive type combination;
• measuring the abrasive flow rate through the at least one blast hose to determine a measured abrasive flow rate;
• comparing, using the controller, the measured abrasive flow rate with the optimum abrasive flow rate range;
• and
• if the measured flow rate is outside the optimum abrasive flow rate range actuating via the controller the abrasive metering valve to open or close the abrasive metering valve to thereby bring the measured flow rate within the optimum abrasive flow rate range;
• wherein the method further comprises:
• providing a solenoid valve positioned on the at least one blast hose, wherein the controller is configured to send toggle signals to the solenoid valve if the abrasive flow rate is below the lower limit for a predetermined period, so that the solenoid valve closes and opens several times, promoting a higher pressure in the pneumatic abrasive blast pot arrangement than in the blast hose and forcing possible blockages in the abrasive metering valve out and into the blast hose.