Foot operated control valves (foot guns) are designed for smooth, reliable operation.  They are easily rebuilt in the field in 30 seconds by unscrewing the dump tube, which removes the used valve assembly.  The operator then snaps a new cartridge style valve in to the dump tube adapter and returns the whole assembly to the gun. To prevent low pressure water from the flex lance nozzle spraying back towards the operator, it is recommended that a Nozzle Shut-Off Valve (Part No. 60-101-050) is used between the foot gun and the flex lance.  This will help to minimize cleanup at the end of the job and greatly assist the operator when inserting the lance in to the next tube. Strain Relief Whip Hoses (Part No. 43-004-003) are designed to relieve the forces on the flex lance end fitting, which extends the life of the lance, and reduces the risk to the operator associated with the end fitting falling prematurely.