Hydraulic accumulator sets built as parallel systems of several pumps are designed for pumping water, raising water pressure in supply networks, and compensation of hydraulic losses resulting from the parameters of supplied pipelines.
The pumping sets are designed to supply potable water and/or treated utility water without solid sediments at a temperature below 120oC. Maximum operating pressure of the set: 10 bar.
Basic technical data
||100 ÷ 3000 m3/h
||15 ÷ 90 m
|pumped liquid temperature
||max 120 oC
|Range of installed power [kW]
||3,0 ÷ 200
- The second and successive pumping stages in water supply systems.
- Industrial process water systems (cooling systems, flushing systems, etc.).
The hydraulic accumulator sets are systems of several pumps that usually have the same size and which are connected in parallel to the supply and delivery manifolds by non-return and cut-off fittings. The set pumps are installed on a support structure made of steel sections. The support structure features vibration dampers that allow setting the set directly on floors.
The ZHN and ZHM hydraulic accumulator sets are based on parallel connections of NHV and MVA/B single-stage centrifugal pumps.
The NHV pumps are installed on separate base plates and connected via flexible couplings to standardised induction motors of a defined size.
The MVA and MVB pumps are monoblock designs with the motor cage and pump impeller installed on the same shaft.
Support structure and manifolds
The support structure of the ZHN and ZHM sets is always specified with the customer. This is required by the large overall dimensions of the compact pumping system. The manifolds and the support structure of pumps and manifolds are made of welded structural carbon steel with dip zinc coating. They are also available made of austenitic steel. The sets feature high quality non-return and cut-off fittings.
|It is always possible to customise the solutions to detailed requirements concerning every aspect of the offered set.
There are several control types for the pumping sets offered, due to the wide variety of applications.
|Adjustment using a rolling (switchable) frequency converter. The control unit is a microprocessor-based controller.
|Cascade control (on/off). The control unit is a microprocessor-based controller.
|Control by a frequency converter linked to a single pump with all other pumps switched on in a cascade. The control unit is a microprocessor-based controller.
|Control and adjustment with a frequency converter with an onboard controller featuring an application for control over the pumping sets. The control unit is a microprocessor-based onboard controller of the frequency converter.
Cascade control with the individual pumps started by voltage thyristor soft start and stop devices.
|Design version according to individual and precise customer requirements.
Features of the microprocessor controller used in standard ZHM, ZHN set control systems:
- Pump speed control depending on the delivery manifold pressure (in an FC system, h = 1). The control system maintains a constant pressure or its specified values in a defined interval by switching various pumps on and off, and adjusting the RPM of the pump that is currently connected to the frequency converter.
- Switching the pumping unit on and off depending on the delivery manifold pressure (in a cascade system, h = 2). The control system maintains a constant pressure or its specified values in a defined interval by switching various pumps on and off.
- Starting of successive pumping units in the set (by a frequency converter or directly from the mains, or optionally by a thyristor soft starter).
- Pump running time balancing: equalisation of the usage rate and test running of pumps in a set that provides fire water supply (all identical pumps of the set). In this function the first pump to be started is the pump with the shortest running time or with the longest standstill.
- It also prevents starting of more than one pump at the same time. It is possible to set a time delay after which the next pump in the set will start.
- Stopping and switching the set to standby in periods of zero demand.
- Stopping of pumps at programmed permissible pressure setpoints.
- Adjustment of the system's performance of the supplied pipeline characteristics by discrete adjustment of pressure setting values in relation to the number of running pumps or preset measured flow rate (optional connection to a flow meter).
- Readouts of all measured operating parameters.
- Adjustment of parameter settings in relation to time interval settings (option).
- The control system automatically switches to cascade operation when the frequency converter fails.
- The control system enables switching to manual mode when the controller fails.
Features of the controller software:
- Collection of data about the values measured in the last seven days.
- Memory of all operating state changes of the set with precise event times (storage capacity: 1000 events).
- Collection of data about individual pump running times.
- Export/transmission of data packages over a serial link in an agreed format to external devices (radio modems, phone modems, GSM modems, PCs).
The control system is installed in a cabinet with an IP54 enclosure. The cabinet size depends on the hydraulic accumulator set size. The cabinet sizes are listed in the set dimensioning tables. The cabinet structure is metal with powder coating. The cabinet has an independent support structure (vertical frame) that accomodates any installation orientation. One end of the structure rests on vibration dampers and the other is fixed to the support structure of the pumps.
The control cabinet front door features:
- The controller ZZ wa front panel with the operator's control panel;
- Operation mode selector switches for individual pumps (operation mode switching: hand/automatic);
- Start and stop switches for individual pumps;
- Operating status and failure alarm indicators.
- "Power Failure" indicator;
- "Dry run" indicator.
The side panel of the control cabinet features the main switch.
|Dry run protection
The set pumps are protected as standard from dry running by conductive measurement probes installed in the main bodies of pumps (ZHM, ZHN). In addition, a set that is operated with an open reservoir can feature float switches or a system of conductive measurement probes, or work with a hydrostatic probe that controls the reservoir filling. In this version the set has no pressure transducer on the supply manifold. A set operated on a water supply system has the pump dry run protection with the aforementioned conductive measurement probes and a pressure transducer on the suction/supply manifold. The available optional protection includes an LCA pressure switch installed on the suction/supply manifold of the set.
Installation site considerations:
- The room area should enable installing the hydraulic accumulator set with clearances that enable free access to individual components.
- The ambient temperature at the installation site should be between +5oC and + 40oC.
- The room should feature a ventilation system with an air exchange rate of 1/hour or higher.
- Due to the foundation of the set on vibration dampers with levelling, no extra foundation works are necessary for the installation.
- The room floor should have a slope towards floor drains for effective water discharge from the installation site. The running hydraulic accumulator set must be protected from flooding with water.
- If the set is fed by an open storage reservoir, the hydraulic accumulator set should be located to ensure a minimum static flow of 1.0 m at the set connection point. Otherwise contact the manufacturer to select and install a suitable flooding adapter.
Features of sets
- The design (shape, form and materials) of the set and its control functions is fully adapted to detailed requirements of the customer.
- The applied pumps (up to the capacity Q = 600 m3/h) comply with PN-EN-733 and assure full interchangeability.
- The traditional single-stage centrifugal horizontal pumps increase durability and operating life of the set with significant simplification of maintenance and servicing.
- The set design enables servicing without stopping the entire pumping unit.