Abstract: A system and method for nematode extermination in lawns using an array of insulated heat blankets (2) placed on the lawn, and energized in a controlled sequence to raise the soil temperature to an effective degree and depth to exterminate nematodes. An electric current controller such as a programmable logic controller (PLC) activates a first subset of the blankets (2) until they reach an upper setpoint temperature, then maintains the blanket temperature within a desired range with reduced current while activating additional blankets. The heat penetrates the soil over a period of about 20 to 50 hours to raise the temperature to at least about 52° C. (125° F.) at a sufficient depth such as at least 12 cm (4.7 inches) to kill at least most nematodes.

Abstract: A steam trap is provided with two paths through which fluid flows from its nput to its output. One path constitutes a control path wherein a small amount of steam or condensate continuously flows through restrictive orifices connected in series between the input and the output. The other path constitutes a main flow path in which a quiet throttling element having a plurality of resistive flow passages and having a moveable valve plug, controls the amount of fluid flowing therethrough. The position of the valve plug and a control piston connected thereto is a function of the fluid flow through the control path between the two orifices; the input and discharge fluid pressures; and a spring connected to the control piston.