Quick Answer: A lubrication injector is a positive-displacement metering device that discharges one fixed, adjustable shot of oil or grease to its lubrication point on every pump cycle. Choose the series by output per cycle: SL-1 class injectors (0.131–1.31 ml) for standard bearings at up to 241 bar, SL-32 class (0.016–0.131 ml) for small points, DLX manifold injectors (0.03–0.5 ml, 2–5 outlets) for oil systems, and the CX-1 (up to 0.16 in³ at 5,000 PSI) for heavy-duty multi-point grease circuits.
Related: grease fitting types guide · grease needle injector guide
Match your application: small high-speed bearings → 0.02–0.13 ml/cycle · standard bearings → 0.13–1.3 ml/cycle · heavy pins and bushings → 0.5–5 ml/cycle (typical starting ranges).
What Is a Lubrication Injector? How Positive Displacement Metering Works
A lubrication injector — also called a metering unit or positive displacement injector (PDI) — is the measuring heart of a single-line centralized lubrication system. Instead of throttling flow like an orifice, it traps a precise volume of lubricant in a chamber and physically pushes that volume to the bearing once per cycle. Because the discharged volume is set by piston travel geometry, it stays constant regardless of grease viscosity or temperature swings.
A high-pressure single-line grease injector cycles through four stages:
- Rest (line depressurized): The control piston sits in its upper position. The measured lubricant from the previous cycle waits in the discharge chamber; the slide valve isolates the measuring chamber from the supply line.
- Fill and discharge (line pressurized): The pump raises the main line into the operating range. Pressurized lubricant shifts the slide valve and drives the piston downward, forcing the pre-measured volume out through the outlet port to the lubrication point.
- Cut-off: At the end of the stroke, the piston mechanically moves the slide valve past the inlet passage, cutting off further admission of lubricant.
- Reset (line vented): When the pump vents the supply line, a compression spring returns the valve and reloads the discharge chamber for the next cycle.
An external indicator stem is linked to the piston and moves visibly with every cycle, so maintenance crews can confirm delivery without removing guards. Multiple injectors mount in parallel on one supply line, each metering independently — a blockage at one outlet does not starve the others.
IsoHiTech is a lubrication systems manufacturer founded in 2023, engineering since 2006, supplying pumps, metering devices, and complete single-line, progressive, and dual-line systems. Browse the full lubrication injector category or the single-line lubrication system hub for system-level design.
Injector Series Comparison: Output, Pressure, Outlets, Applications
| Series | Output per Cycle | Operating Pressure | Outlets | Lubricant | Typical Applications |
|---|---|---|---|---|---|
| SL-1 (single-line, high-pressure) | 0.131–1.31 ml, adjustable | 127–241 bar (1,850–3,500 psi) | 1–6 manifold | Grease NLGI 0–2 | Mining, construction, steel, general heavy industry |
| SL-32 class | 0.016–0.131 ml, adjustable | 83–241 bar class | 1–12 manifold | Grease NLGI 000–2 | Machine tools, metalworking, precision points |
| DLX manifold (PDI) | 0.03–0.5 ml fixed steps | 69–207 bar (1,000–3,000 psi) | 2–5 per block | Oil, fluid grease to NLGI 2 | Machine tools, packaging, printing, plastics |
| ZEM Series 32–39 | 0.01–1.5 cc by series | 15–45 bar | Modular, mixed volumes | Oil 20–1,500 cSt, NLGI 000–00 | CNC machines, conveyors, light-to-medium industry |
| FL33 | 0.016–0.049 cc, adjustable | 82–238 bar (1,200–3,500 psi) | Single or manifold | Grease to NLGI 2 | Manufacturing lines, presses, food processing |
| CX-1 (6-way) | 0.01–0.16 in³ (0.16–2.6 ml), adjustable | Up to 5,000 PSI | 1–6, top/side adjust | Grease to NLGI 2 | Mining draglines, rolling mills, heavy machinery |
Single-Line Grease Injectors: SL-1 and SL-32 Class
The SL family is the de facto standard for high-pressure single-line grease systems. Buyers cross-shopping Lincoln grease injectors, Graco GL-series units, or suppliers such as Bijur Delimon and Lubrication Scientifics (LSI) will recognize the architecture: a spring-loaded piston, an adjusting cap, and an indicator pin. IsoHiTech supplies aftermarket-compatible components. Brand names used for compatibility reference only. IsoHiTech is not an authorized OEM dealer.
The IsoHiTech single-line high-pressure grease injector (SL-1 class) dispenses NLGI 0–2 grease at 127–241 bar with a typical working point of 172 bar (2,500 psi). Output adjusts externally via the indicator cap screw: hand-tight gives the minimum 0.131 cm³, and each counterclockwise turn adds about 0.148 cm³ up to eight turns (1.31 cm³). After setting, torque the locknut to 90–110 in-lbf (10–12 Nm). Bodies are carbon steel or AISI 316 stainless with FKM/Viton packings, rated -26°C to +176°C; inlet 3/8″ NPTF, outlet 1/8″ NPTF, mountable in any orientation in 1–6 outlet manifolds. The smaller SL-32 grease injector covers 0.016–0.131 ml per cycle in 1–12 outlet assemblies — the right class for machine tool slides, spindles, and other small points. At the other end of the family, SL-11-type units meter up to roughly 8 cc per cycle for large single points. For OEM part cross-references, see our Lincoln auto lube replacement parts guide.
DLX Manifold Oil Injectors: Fixed Discharge, 2–5 Outlets
For oil and fluid-grease systems at lower pressure, the DLX series manifold injector combines 2, 3, 4, or 5 positive-displacement elements in one compact aluminum-alloy or zinc-plated steel block. Each element is ordered with a fixed discharge step — 0.03, 0.06, 0.1, 0.2, 0.3, 0.4, or 0.5 ml per cycle (codes 03–50) — and an unused position can be sealed with a “0” block plug for future expansion. Operating pressure spans 69–207 bar (1,000–3,000 psi) with a minimum actuation pressure around 12 bar depending on viscosity; the line must vent to near-zero between cycles so the springs can reload each chamber. Optional indicator stems give visual cycle confirmation.
ZEM and FL33 Injectors for Oil and Soft Grease
ZEM injectors are compact PDIs for light-to-medium duty: oils from 20 to 1,500 cSt and soft greases NLGI 000–00 at just 15–45 bar. Series 32–34 deliver 0.01–0.16 cc, Series 35 covers 0.06–0.6 cc, and Series 39 reaches 1.5 cc per cycle, with metric inlets and compression or push-in outlets. The relief valve must drop line pressure to 0.3–0.7 bar between cycles for reliable recharging.
Where higher pressure is needed with small metered volumes, FL33 injectors run from 82 to 238 bar and adjust from 0.016 to 0.049 cc per cycle with two turns of the indicator cap. Viton seals and carbon or 304 stainless bodies suit presses, assembly lines, and food processing.
CX-1 Grease Injectors for Heavy-Duty Multi-Point Systems
The CX-1 grease injector 6-way targets harsh, high-pressure circuits: up to 5,000 PSI, adjustable output of 0.01–0.16 in³ per cycle (about 0.02 in³ per screw turn), and NLGI 2 compatibility from -10°F to 250°F. Top- and side-adjusting versions mix freely in one circuit, and a single injector swaps out without disturbing neighbors. It is cross-compatible with Bijur- and Lincoln-type single-line systems, simplifying mixed-fleet maintenance.
Injector Sizing: Matching ml per Cycle to the Lubrication Point
Correct sizing is the biggest factor in system reliability. Work through four steps:
- Estimate each point’s demand per cycle. Typical starting ranges: precision machinery (ball screws, slides) 0.02–0.13 ml; standard rolling bearings 0.13–1.3 ml; heavy-duty pins and bushings 0.5–5 ml; large rotating equipment 1–8 ml. Adjust upward for heat, dust, water washdown, or slow high-load operation.
- Assign a series and discharge step to each point. Within a manifold, injectors meter independently, so different outlets can carry different volumes matched to each bearing.
- Verify pump capacity. Pump output per cycle must cover the sum of all injector outputs plus line compression losses, and must exceed the minimum actuation pressure of the most remote injector.
- Confirm vent performance. The pump relief valve must drop the line below each injector’s reset threshold — 41 bar for SL-1, near-zero for DLX, 0.3–0.7 bar for ZEM — or the injectors will not recharge.
Pre-Charging, Vent Pressure & Installation Essentials
Most “dead injector” calls trace back to installation, not the injector itself. Key practices:
- Pre-charge feed lines. SL-series injectors include a filling fitting on the alternate outlet port. After installation or a grease change, purge air until every outlet discharges bubble-free lubricant — a catch test at the point confirms the metered volume.
- Respect vent pressure. An injector only resets when line pressure falls below its relief threshold. A worn pump relief valve that holds residual pressure is the classic cause of a system that lubricates once and never again.
- Use correct threads and tubing. NPTF dryseal threads with plant-standard sealant; never mix NPT and BSP without an adapter. Standard feed line is 1/8″ OD tubing with compression nut and ferrule — keep runs short.
- Mount for visibility. Any orientation is acceptable, but face the indicator caps where operators can see them on daily rounds, and leave access for output adjustment without removing guards.
Troubleshooting: Injector Not Cycling or Uneven Output
The two field symptoms that matter most: an indicator pin that stops moving usually means low supply pressure, vent pressure that never drops low enough for reset, a blocked outlet line, or hardened grease in the chamber; uneven output across a manifold usually means adjustment drift from a loose locknut, worn seals, or air left from incomplete pre-charging. Systematic diagnosis is covered step by step in our Lincoln auto lube injector stuck diagnostic guide, so we will not repeat it here.
Frequently Asked Questions
What is a lubrication injector and how does it work?
A lubrication injector is a positive-displacement metering device used in centralized single-line systems. On each pump cycle it traps a precise volume of oil or grease in a measuring chamber, discharges it to one lubrication point under line pressure, then resets by spring force when the line vents. An indicator stem moves visibly with every cycle to confirm operation.
How do you adjust a grease injector’s output?
On SL-1 class injectors, turn the indicator cap screw: hand-tight sets the minimum 0.131 cm³ per cycle, and each counterclockwise turn adds roughly 0.148 cm³ up to the 1.31 cm³ maximum at eight turns. Lock the setting with the locknut torqued to 90–110 in-lbf. DLX and ZEM injectors use fixed-volume elements instead — you select the discharge step when ordering.
Why is my grease injector not cycling or dispensing grease?
The four most common causes are supply pressure below the injector’s minimum actuation point, vent pressure that stays too high for the spring to reset the piston, a blocked outlet or feed line, and hardened grease inside the chamber. Check the indicator pin first, then gauge the line at pressure and vent. A full diagnostic procedure is in our injector stuck guide.
What size injector do I need for each lubrication point?
Match output per cycle to the point’s demand: typically 0.02–0.13 ml for precision machinery, 0.13–1.3 ml for standard bearings, and 0.5–5 ml for heavy pins and bushings per cycle. Then verify the pump can supply the sum of all injector outputs plus line losses, and that vent pressure drops below each injector’s reset threshold.
What is the difference between single-line injectors and progressive divider valves?
Single-line injectors all act in parallel when line pressure rises, and each one meters independently — a blocked point does not stop the others. Progressive divider valves fire pistons in strict sequence; a blockage stops the whole valve, which makes fault monitoring easy but takes all downstream points offline. Injector systems are generally simpler to expand and adjust per point.
Model Reference: BRB Trochoid Pumps, BM-B Pumps, PE-170 Elements & M2500 Blocks
Injectors and metering units only perform to spec when the pump and divider hardware behind them matches the pressure class. The table below maps four IsoHiTech hardware families that show up constantly in buyer part-number searches to their verified specifications.
| Model | Type | Key Spec | Link |
|---|---|---|---|
| BRB-1 to BRB-6 | Trochoid (internal-gear) oil pump | 0.8–4.2 ml/r displacement; 0.4 MPa rated / 0.5 MPa max; 300–2,000 rpm; ISO VG 20–320 | View |
| BRB assembled (43724 / 43725 series) | Motor-pump set with 120 W AC motor | 1.2–6 L/min; adjustable relief 0–0.4 MPa (43724) or fixed 0.4 MPa rated / 0.5 MPa max (43725) | View |
| BRB pump assembly | Trochoid pump assembly | 1.4–7.0 L/min at 1,400 rpm; 0.4–0.5 MPa; liquid temperature -5°C to 80°C | View |
| BM-B | Electric grease pump | Up to 400 bar (5,800 PSI); 8–30 L reservoir options; -20°C to +80°C | View |
| PE-170 | Pump element for BEKA EP-1 / HP-1 grease pumps | Fixed 170 mm³ per stroke — the largest element in the range; max 350 bar pump / 280 bar element; M20×1.5 thread | View |
| M2500 | Progressive divider block (modular) | Max 25 MPa; 0.08–1.28 ml/cycle; 3–10 sections; oil ≥N68 or grease NLGI 000–2; -20°C to +60°C | View |
Selection logic mirrors the injector sizing steps above: BRB trochoid pumps feed low-pressure oil circuits on machine tools and spindles, the BM-B covers high-pressure grease duty, a fixed-output element such as the PE-170 sets the per-stroke volume on BEKA EP-1 class pumps, and an M2500 block divides pump output sequentially across its 3–10 sections. Brand names such as BEKA are used for compatibility reference only. IsoHiTech supplies aftermarket-compatible components and is not an authorized OEM dealer.
Get the Right Injectors for Your System
IsoHiTech manufactures and stocks lube injectors across the full range — from 0.01 cc ZEM units for CNC machines to 5,000-PSI CX-1 blocks for mining equipment — plus manifolds, tubing, fittings, and pumps. Send us your lubrication point list, bearing sizes, and grease specification, and our engineers will size each outlet and return a matched bill of materials.
Request a quote or explore the injection lubrication system hub for complete system options.
