Circulating Sub

The Darron Circulating Sub has been designed to achieve increased mud circulation by placement in the Bottom Hole Assembly (B.H.A.), either above the bit or down hole motor to pump materials in case of lost circulation.

Activation is accomplished by dropping a chrome steel ball down the drill string and then engaging the mud pumps. On application of 3000 psi fluid pressure, the ball shears the pin holding the sleeve in its primary position. The sleeve and pin drop into the secondary position, opening the three sub ports and diverting the downhole flow.

Darron Circulating Subs are manufactured from AISI 4145 H material fully heat treated to give 285-341 BHN and are available in the same nominal diameters as standard drill collars or to customers' own specifications.