SL1 Grease Injector
The SL1 grease injector is a single-line, positive-displacement metering device for centralized oil or semi-fluid grease circuits. Each pressure cycle delivers an adjustable dose to one bearing or branch line—ideal when progressive blocks are too large or points are widely spaced on machine tools, packaging lines, and mobile equipment.
Highlights:
- Operating pressure: 6.5–20 MPa (950–2,900 psi class)
- Adjustable output: 0.050–0.500 cu.in. (0.82–8.2 cc) per cycle
- Seals: standard Viton O-rings (70 durometer) and Hytrel packings for heat and synthetic media
- Indicator pin for visual cycle confirmation
- Feed-line fill fitting for priming
- Vinyl cover caps on all injectors at shipment
- Ports: inlet 1/2″ NPT; outlet 1/4″ NPT
- Body: steel with zinc and yellow chromate plating
- Max temperature: 200°F (93°C) (media dependent)
Pair with positive injector systems, lubrication injectors hub, SL32 grease manifold, and single-line architecture. Pumps: FS grease pump, electric grease pump, LSG hand pump (soft grease).
- SL1 Operating Principle
- Parameter Table
- The Dimension Diagram
- SL1 vs SL32
The SL1 injector meters on each pump cycle of a single-line PDI header. Lubricant enters under pressure, fills a measuring chamber, and displaces a piston that delivers grease or oil to the point. A vent/relief cycle (typically ≤ 150 psi / 10 bar on the line) lets the piston return and recharge. The external adjustment screw sets stroke volume for the application.
Install in cramped areas along the main line—distance between points is limited by hose/tube pressure drop, not injector body size. Standard or custom manifolds mount multiple SL1 bodies on one bracket for multi-outlet headers.
| Parameter | Value |
|---|---|
| Operating pressure | Max 20 MPa; minimum 6.5 MPa |
| Lube output (adjustable) | 0.050–0.500 cu.in. (0.82–8.2 cc) per cycle |
| Vent / relief pressure | ≤ 150 psi (10 bar) |
| Lubricants | Oil; semi-fluid grease (NLGI #000–#1 typical) |
| Seals | Viton O-rings + Hytrel packings |
| Max temperature | 200°F (93°C) |
| Material | Steel, zinc + yellow chromate |
| Inlet | 1/2″ NPT |
| Outlet | 1/4″ NPT |
| Model | Outlets | Pressure | Typical discharge | Best for |
|---|---|---|---|---|
| SL1 (this page) | 1 per body | 6.5–20 MPa | 0.05–0.50 cu.in/cyc | Single-point or custom manifold |
| SL32 | 1–12 manifold | 8–24 MPa | 0.016–0.131 ml/cyc × outlets | Multi-point grease PDI |
| DLX oil PDI | 1–5 | 0.8–1.5 MPa | 0.1–0.5 ml/cyc | Oil only—not grease |
SL1 Cycle Sequence
- Rest / recharge — piston holds lubricant from the previous cycle; line at low pressure.
- Pressure on — pump builds header pressure; slide valve opens; measuring chamber fills.
- Discharge — piston strokes; metered volume exits the 1/4″ NPT outlet to the bearing.
- Vent / relief — line pressure drops to ≤150 psi class; spring returns piston; injector ready for next cycle.
Installation Checklist
- Mount with indicator pin visible for inspection.
- Set output screw per OEM ml/cycle chart; lock after adjustment.
- Prime feed line via fill fitting before first production run.
- Use grease filter on fill in dusty plants.
- Do not mix SL1 on the same header with progressive blocks without system engineering review.
OUR WORKSHOP
Where the SL1 Fits in a Centralized System
The SL1 is a point-level meter on a single-line positive-displacement injector (PDI) header—not a pump and not a progressive divider. A typical grease PDI plant looks like this:
- Pump + controller — electric, pneumatic, or manual source (FS, motorized, or LSG for soft grease).
- Main supply line — steel or nylon tubing sized for 6.5–20 MPa and NLGI #000–#1 flow.
- SL1 injector(s) — one body per point, or several on a custom manifold bracket.
- Branch line — short hose or tube to bearing, slide, cam, or chain point.
On each cycle the controller runs the pump until line pressure rises; every SL1 on that header that reaches opening pressure strokes and delivers its set dose; then pressure is vented and injectors recharge. Injectors on a common line act in parallel during the pressure-on phase—unlike progressive blocks, which meter in strict sequence.
SL1 vs SL32 vs Progressive (Quick Pick)
| Architecture | Metering device | When to use |
|---|---|---|
| SL1 PDI (this page) | One adjustable injector per body; up to ~8.2 cc/cycle | Few points, high dose each, custom spacing, oil or semi-fluid grease |
| SL32 manifold | Factory block, 1–12 outlets, smaller ml/cyc per port | Many grease points, uniform small doses, 8–24 MPa class |
| DJF progressive | Sequential slices, 3–20 outlets on one chain | NLGI #000–#2 on one sequential header; cycle indicator monitoring |
| DLX oil PDI | Low-pressure oil injectors | Spindle / way oil only—not for grease |
Five-Step SL1 Sizing
- Dose per point — from bearing OEM chart (convert to cc/cycle).
- Adjust SL1 screw — set within 0.050–0.500 cu.in. range; verify with catch-and-weigh on first commissioning.
- Count injectors — sum doses; confirm pump flow and stroke rate can supply all points each cycle.
- Pressure check — farthest injector must see ≥ 6.5 MPa at opening; long runs may need larger tube ID or higher pump class.
- Relief/vent — ensure controller vents to ≤150 psi class so pistons return; stuck-high pressure = no recharge.
Common Field Issues
- Pin never moves — blocked outlet, air lock, pump not reaching 6.5 MPa, or grease too stiff (step down NLGI or warm fill).
- Under-delivery — adjustment screw backed off, worn seals, or partial stroke from rapid vent.
- Leaks at NPT — use thread sealant rated for grease; do not over-torque on steel body.
More context: lubrication injectors hub · PDI systems guide · injection lubrication system.
Before you buy: read our grease fitting types guide.
The SL1 is a single-line grease or oil injector for centralized PDI systems. It delivers a fixed adjustable dose per pump cycle to one lubrication point or branch.
6.5 MPa minimum to 20 MPa maximum. Size the pump and header so the farthest injector sees opening pressure on every cycle.
Externally adjustable from 0.050 cu.in. (0.82 cc) to 0.500 cu.in. (8.2 cc) per cycle via the setting screw.
Light oil and semi-fluid grease (typically NLGI #000–#1). Confirm compatibility with Viton/Hytrel seals before using synthetic or high-additive greases.
Inlet 1/2″ NPT; outlet 1/4″ NPT. Adapters available via compression fittings and couplings.
Yes—IsoHiTech supplies standard or custom manifolds for multiple SL1 bodies on one machine header.
316 stainless bodies are available on MOQ for corrosive environments; standard production is zinc-chromate steel.
Watch the indicator pin each cycle. No pin movement with rising line pressure indicates blocked outlet, under-pressure pump, or stuck piston.
Inspect every 3–6 months (monthly in harsh duty). Replace if output drifts, seals leak, or pin stops cycling.
Use SL1 for individual high-dose points or custom layouts; use SL32 when you need 1–12 outlets in one factory manifold body.