The valves are produced as straight-through, with welded ends and connection dimensions according to TP 422 – C – 113 – 83 in nominal size DN 50 and calculating pressure of 8,6 MPa. The body is casting made of WN 1.4552 (stainless steel). The outer surface of the body is not machined except for weld ends. No scales, rust and cracks are allowed to be on the body. The throttling trim consists of one-step contoured plug and seat. The plug is made of 17 247.4 (stainless steel). Seat is made of 17 134.7 (stainless steel). The flow section and shape of control trim is determined by calculation. The valves are equipped with linear flow characteristic (in case of customer´s request, it is possible to have equal-percentage or parabolic flow characteristic as option). The permissible deviation in slope of linear or equal-percentage flow characteristic is +- 30 % according to ČSN 13 4509-5.
The stem is sealed with 4-jacket bellows with safety packing consisting of graphite rings. The body and bonnet sealing to environment consists of 3 sealing rings made of graphite. The valve fulfills the requirements for absolute tightness to outer environment.
The valves are equipped with stroke indicator. The valves are equipped either with hand wheel or assembled with an electromechanic actuators of ROTORK type NA. Based on the type of used actuator, the valves can operate both inside of hermetic zone and outside. The valve design enables the valve to be rinsed through as well as the outer surface can be washed with decontamination solutions (electromechanic actuator are to be decontamined on the outer surface only) according to the requirements of VTP 87. The valve is designed the way so that the decontamination solution can be removed (run down). The material of the valve which is not coated with protection paint is resistant to rust with used decontamination solutions. The application of decontamination solutions complies with VTP 87. Regarding the valves not being coated with protection paint and when the process medium does not get in touch with carbon steel with zinc-chrome coating, it is possible to use only the following compounds for rinsing-through: No.6 and No. 7 Acc. to provision. 3.13 VTP.
The control valves series RV 501 NA1 are designed, when assembled with electric actuator of NA type by ROTORK company or equipped with hand wheel, to control the flow and pressure of “condensate at secondary side of the circuit (feeding water)” Acc. to VTP 87 section No. 1, article 12. The valves are produced in nominal size DN 50. The max. permissible leakage rate for this type of valves is set to 0,05 % of Kvs. In case of special request by the customer, the leakage rate can not exceed the value mentioned in the purchase contract concluded. The classification zone is 2 B II and according toVTP 87. The valves are produced and delivered for the following parametres of the process medium according to VTP 87: Max. operating pressure 8,6 MPa. Max. operating temperature 300°C.
The valves is actuated with ROTORK 7NA1 actuator type. It is a multi-turn electric actuator with low inertia torque and with high control torque. The valve is also equipped with hand wheel for manual operating. The setting the valve into manual operation mode is carried out by the lever manual/auto whcih is lockable and after setting to manual mode the power supply automatically switches off. Due to the manual operating, the valve is equipped with mechanical stroke indicator besides resistance position transmitters. Further it is equipped with limit switches limiting the operating stroke travel and also with torque switches which ensure switching off in case of damage to limit switches and so the internal parts of the valve (such as stem with bellows and plug, seat, etc.) are protected against damage.
The actuator is sealed by the producer which is a garantee that the valve passed all the test required. These valves can operate both inside of hermetic zone and outside. The actuator is connected to the valve with standardized coupling (flange F10), which ensure interchangebility of the actuators for example in case of damage or due to any other reasons.