to the afterflow time and close time and determines the parameters used to enter the shut in cycle 305 when a dry plunger is detected a dry plunger means that the plunger 17 reached the top of the production string 20 without any accompanying fluids this scenario is not within the normal operation of the well and may indicate that the plunger 17 is not reaching the bottom of the production string 20 during the fall cycle 309 this is a dangerous situation because a dry plunger can hit the upper bumper spring 4 at a much higher velocity than normal which can damage or rupture the top of the well typically plunger 17 speed is not directly measured instead an abnormally short plunger arrival time is assumed to indicate excessive plunger speed and a dry plunger if the plunger arrival time is less than a time limit corresponding to the safest maximum plunger speed the controller system will close plunger lift control valve 10 and enter the shut in cycle 305 during a normal operating cycle the microprocessor enters the close cycle 303 u201c close u201d refers to the state of the plunger lift control valve 10 as controlled by the microprocessor a.