What a Dual Line Pump Does
The BSB pump is the supply side of a dual line centralized grease system. One pump alternates grease between two main lines, and each main line carries grease outward to dual line valves that meter it to the lube points. Alternating the two lines lets one pump cover long pipe runs and large point counts that would strain a single-line layout. The pump pressurizes the first main line, the reversing control shifts flow to the second main line, and the sequence repeats as the system demands.
Parts lists code this pump family BS-B — BSB is the compressed form. It is an electric supply pump for dual-line circuits feeding ZV-B distributors, and this is our own manufacture, built as a direct replacement wherever a BS-B pump is specified.
A dual line system is a central lubrication system in which the pump, the reversing valve, the end-of-line monitor, and the metering valves work as one chain. The central lubrication overview shows where that chain sits on a machine. This page covers the pump only; the reversing valve and the end-of-line monitor have their own pages, linked from the answers below.
One distinction matters before ordering. A system pump like the BSB builds line pressure and feeds valves on a machine. A filler pump only moves grease from a drum or container into a reservoir and never builds line pressure. The BSB is a system pump, sized and selected against the valves it feeds.
Models and Specifications
Three models share the same 40 MPa (400 bar) maximum working pressure and differ in output, motor, and duty. All three run on a 380 V three-phase supply.
| Item | Specification |
|---|---|
| Maximum working pressure | 40 MPa (400 bar) |
| P120Z output | 120 cm3/min at 80 rpm |
| P235Z output | 235 cm3/min at 160 rpm |
| P365Z output | 365 cm3/min at 250 rpm |
| Motor | 0.37 kW on P120Z, 0.75 kW on P235Z, 1.5 kW on P365Z, 380 V three-phase |
| Reservoir options | 30 L, 60 L, or 100 L |
| Operating temperature | -20°C to +80°C |
| Lubricant | grease NLGI 000 to 2; oil above 68 cSt |
Model choice starts from system flow demand, not from motor size; the sizing logic follows.
How the Mechanical Reversing Works
The reversing control is a dual-acting feed piston with a mechanical pilot control. The pilot piston is driven by line pressure itself: when the active main line reaches the switching condition, line pressure moves the pilot piston and the pump changes direction. The pump switches between the two main lines without any external control signal, which removes a control cable, a signal source, and a settings step from the installation.
Because the pilot piston runs on line pressure, the pump follows the system state directly. The alternation stays in step with what the valves actually pass per pressure cycle.
Sizing the Pump to the System
The pump and the valves must be chosen as a system. Pump capacity must cover all valve outputs within the cycle time: add the outlet volume of every dual line valve in the system, then check that the selected model can deliver that volume within one pressure cycle at its rated speed of 80, 160, or 250 rpm. The P120Z at 120 cm3/min suits compact systems, the P235Z at 235 cm3/min suits mid-size layouts, and the P365Z at 365 cm3/min suits the largest point counts.
Keep two pressure figures separate during selection: the pump maximum working pressure of 40 MPa (400 bar), and the valve switching pressure that makes each valve change position. A system can need full pump pressure to push cold grease through long lines while the valves switch far lower. Confirm both figures against the valve data before ordering. If the sizing arithmetic is unclear, send the valve count and outlet volumes through the quote contact page and the pump will be matched to the system.
For the wider pump family and where the BSB sits within it, see lubrication pumps for industrial automated lubrication systems.
Reservoirs, Refilling, and Air
The 30 L, 60 L, and 100 L reservoirs are chosen from three facts: total grease consumption per lubrication round, refill access at the machine, and the installed space around the pump. A system with many large points consumes more grease per round and pushes the choice toward 60 L or 100 L. A compact machine with easy refill access can stay on 30 L. State the consumption per round and the available space when ordering, and the reservoir follows from them.
After every refill, vent air pockets from the reservoir before resuming cycles. Trapped air feeds into the main lines, delays pressure build-up, and can stall the first cycles after a refill. Run the vent path per the installation drawing until grease free of air passages reaches the pump inlet, then restore normal operation.
Between refills, check the reservoir level during routine walkdowns and refill when the level drops near the low mark. Keep the vent path clear and the grease surface clean so the pump does not draw in debris.
Grease Grades and Temperature
The pump handles grease from NLGI 000 to NLGI 2. NLGI 000 is the softest grade in this range and NLGI 2 is the stiffest; the grade number rises as the grease gets stiffer. The pump also moves oil above 68 cSt. The declared operating band is -20°C to +80°C.
Stiff grades in cold conditions need care: grease near NLGI 2 thickens further toward the low end of the temperature band, so the pump works harder to move it through long main lines, while soft grades near NLGI 000 flow with far less resistance. Match the grade to the ambient band and the line length, and confirm seal compatibility with the fluid data sheet before ordering.
Grade selection also interacts with the valves: a grade the pump can move is not always a grade the metering valves pass cleanly at their switching pressure. Confirm both sides against the fluid data sheet. For the neighboring pumps in the family, see the grease pump range.
Frequently Asked Questions
What is a dual line pump?
It is one pump that alternates grease between two main lines in a dual line system. Each line then feeds its own run of dual line metering valves.
What does 40 MPa mean for this pump?
40 MPa (400 bar) is the maximum working pressure of the pump. Valve switching pressure is a separate, lower figure.
Which BSB model should I choose?
P120Z, P235Z, or P365Z by output at 80, 160, or 250 rpm. Size from total valve output per cycle, not from motor size alone.
How does the pump reverse between the lines?
A dual-acting feed piston with mechanical pilot control reverses the pump. Line pressure moves the pilot piston, so no external control signal is needed.
Which reservoir size fits my system?
Choose 30 L, 60 L, or 100 L from grease consumption per round, refill access, and installed space. Larger consumption per round points to the larger reservoirs.
Which greases can the BSB pump handle?
Grease from NLGI 000 to 2, and oil above 68 cSt. Stiff grades near NLGI 2 thicken further in cold and need care.
How does the pump connect to the rest of the system?
The hydraulic reversing valve alternates the two main lines, and the end-of-line pressure unit monitors line completion. Both mount in the main line chain between the pump and the valves.
Can one pump pressurize both main lines at once?
No, the two lines alternate and only one is pressurized at a time. Each dual line valve serves half its outlets per pressure cycle.
What should I do after refilling the reservoir?
Vent air pockets from the reservoir before resuming cycles, so the first cycles build pressure cleanly. For refill and venting details matched to your reservoir, use the quote contact page.
Who builds and supports the BSB pump?
IsoHiTech Lubrication Systems, founded in 2023, engineering since 2006, builds and supports every unit. Email inquiry@isohitech.com for specifications and a quotation.
Related: See the BS-B system walkthrough for the full dual-line cycle with DR45 reversing and ZV-B blocks, or the DR4-5 reversing valve that pairs with it.
