Number of pumps
|FEED-SN — Constant pressure unit with one pump.||FEED-DG — Constant pressure unit with two pumps.|
|FEED-.. / TANK — Constant pressure unit with a water tank (with a water level control system).||FEED-.. — Constant pressure unit without a water tank (to connect to available tanks).|
For customized configurations
|Limitations||Capacity||up to 35 м3/h|
|Pressure in receiver||up to 0,2 barg|
|Pressure produced by pump
||up to 220 m H2O|
|Temperature of pumped medium||up to 180*С|
|Connection to the electricity grid||Determined based on the Questionnaire information|
|For customized configurations|
||Carbon steel*, **|
|Stop valves, strainers and filters, valves
|Ball valves||Carbon steel*|
Carbon steel*, **
* By default. Other materials can be quoted in “Other requirements” section of the Questionnaire
** 316L stainless steel is recommended for use in DHW systems due to highly corrosive secondary heat transfer medium
Dimensions and weight of customized configurations
Custom-shaped for each order based on the information provided in the Questionnaire. For more information, contact Steam Control Engineering, LLC (OOO).
- Water level control in the receiver based on level gauge readings for configuration FEED-../TANK-…
- The “on/off” outlet water pressure control for units with a pressure switch or maintenance of constant outlet pressure based on the readings of an analogue pressure gauge for configuration FEED-..-VFD.
- Pump operation control: with error alarms generation.
- If configuration FEED-DG has been selected: automatic start of a backup pump when the work pump fails.
- If configuration FEED-DG has been selected: automatic change of a primary pump after a specified period of time.
- If configuration FEED-..-VFD has been selected: maintenance of a constant pressure drop across the valve when an additional pressure gauge is connected.
- General alarm (dry contact) and optional configurable digital output.
- Digital input for remote on/off switching of the unit.
- On request: digital interface for connection with the top level of the Computerized Process Control System (CPCS) (Profinet, Modbus, Profibus).
Selection and installation details
|A proper constant pressure unit FEED design is to be made in accordance with local regulations prior to a constant pressure unit FEED installation. All necessary additional pipeline ancillaries, safety and control devices are to be included in order to ensure safe and long-term operation of equipment.|
|For a proper quality of pressure control, it is often necessary to install a diaphragm expansion tank in the delivery line. The dimensions of the expansion tank depend on the set pressure, type of control and other factors. For additional information, please contact “Steam Control Engineering”, LLC (OOO).|
|For configurations without TANK (when an available feedtank with a water control system is used), it is necessary to enable the switching-off of unit pumps against the signal from an existing level control system when the feedtank low level alarm occurs (use digital input in the control system to remotely switch the unit on/off).|
|To provide minimal pump flow and prevent water boiling on the pump blades, installation of a bypass line with fitted with a balancing valve is recommended. In particular, in DHW systems, a circulation loop Т4 can serve as a bypass line.|
|If the unit is used to maintain pressure in feed loops fitted with a control valve (e.g., to control the level in a steam boiler or the temperature in a steam cooler), it is recommended to use an additional pressure gauge installed downstream of the valve. This option will maintain a constant pressure drop across the control valve, thereby improving the quality of control and reduce the risk of cavitation on the valve seat. The unit control system has an additional analogue input to connect such gauge.|