To maximize the effectiveness of the shearer-clearer system, the splitter arm should extend as far beyond the headgate drum as possible, all splitter arm sprays should be oriented with the airflow, a sufficient number of sprays should be used to prevent dust from the headgate drum from migrating to the walkway, and belting should be hung from the splitter arm to help separate face airflow and confine dust. Since the splitter arm should extend beyond the drum if possible, it should be made from sufficiently rigid steel tubing/pipe to withstand coal and rock impacts from the face. Alternately, splitter arms have been observed where springs have been mounted on the arm so that the arm can absorb a blow and bounce back into position. Since directional spray systems are attempting to move air, the operating pressure is critical and pressures of at least 150 psi should be used. Hollow-cone or venturi sprays (Figure 3-8) are effective for these systems. The sprays should be oriented to help move dust along the face without causing turbulence. Thus, it is not desirable to have sprays impacting the ranging arm.