Sight Indicator Plug | Floating Ball Level Indicator | SAE J514 / J1926 – Lumiglas®
Lumiglas® sight indicator plug with floating ball level indicator. SAE J1926 compatible, ORFS seal, PS 35 bar / MWP 500 psig. Drop-in replacement for hydraulic & gearbox drain ports. Request a quote.
Description
Sight Indicator Plug with Floating Ball Level Indicator
The Lumiglas® Sight Indicator Plug is a precision-engineered drain port plug combining a sealed borosilicate glass window with a buoyant high-visibility red floating ball indicator. Fully interchangeable with SAE J1926 and BSP standard drain/fill ports, it delivers real-time fluid presence confirmation without system disassembly or shutdown.
Available in brass as standard — stainless steel and carbon steel on request. Sealed with an O-Ring Face Seal (ORFS) for zero-leak performance up to PS 35 bar / MWP 500 psig, with no thread sealant required.
↓ Download Product Datasheet (PDF)
How the Floating Ball Indicator Works
A buoyant red polymer ball is housed inside the sight window. The indicator state is immediate and requires no calibration or operator training:
| Indicator State | Ball Position | Meaning |
|---|---|---|
| ● FLUID PRESENT | Ball floating — visible at glass face | Fluid at or above port level ✓ |
| ○ FLUID ABSENT | Ball sunk — not visible through window | Fluid below port level or absent ✗ |
Technical Specifications
| Parameter | Specification Details |
|---|---|
| Body Material | Brass (standard) · Stainless Steel · Carbon Steel (on request) |
| Window Material | Borosilicate glass |
| Indicator Ball | Buoyant polymer, Red — high-visibility |
| Seal Type | O-Ring Face Seal (ORFS) — no thread sealant required |
| O-Ring — Standard | Buna-N (NBR) |
| O-Ring — Option | Viton® (FKM) — for refrigerants & aggressive media · suffix -V |
| Thread Standard | SAE J514 (UN 2A) / SAE J1926 port compatible |
| Drive Type | External Hex (spanner flat) |
| Max. Working Pressure | PS 35 bar / MWP 500 psig (507 psi) |
| Max. Operating Temp. | 80 °C / 175 °F |
| Min. Operating Temp. | −30 °C / −22 °F (NBR) | −40 °C / −40 °F (FKM) |
| Compatible Fluids | Hydraulic oil, gear oil, lubrication oil, water-glycol, refrigerants (FKM) |
| Brand / Origin | Lumiglas® / Made in China |
Dimensions & Ordering Reference
SAE J514 · All dimensions in inches · Tolerances: A ±0.01 · B +0/−0.5 · C ±0.003 · D +0.005/−0.006
| Part No. | Size | Thread (UN 2A) | “A” (in) | “B” (in) | “C” (in) | “D” (in) | O-Ring (mm) |
|---|---|---|---|---|---|---|---|
| LMG-00 | 00 | 10–32 | .31 | .12 | .221 | .061 | 3.0 × 1.25 |
| LMG-01 | 01 | 1/4–24 | .44 | .12 | .296 | .125 | 4.5 × 1.5 |
| LMG-02 | 02 | 5/16–24 | .38 | .12 | .348 | .125 | 6.0 × 1.5 |
| LMG-03 | 03 | 3/8–24 | .38 | .12 | .411 | .125 | 7.0 × 1.5 |
| LMG-04 | 04 | 7/16–20 | .45 | .12 | .477 | .188 | 8.0 × 1.5 |
| LMG-05 | 05 | 1/2–20 | .45 | .12 | .540 | .188 | 10.0 × 1.5 |
| LMG-06 | 06 | 9/16–18 | .48 | .12 | .656 | .250 | 12.1 × 1.6 |
| LMG-08 | 08 | 3/4–16 | .56 | .15 | .800 | .313 | 15.6 × 1.78 |
| LMG-10 | 10 | 7/8–14 | .63 | .15 | .930 | .375 | 18.0 × 2.0 |
| LMG-12 | 12 | 1-1/16–12 | .75 | .15 | 1.130 | .563 | 22.3 × 2.4 |
★ Highlighted row (LMG-12) = recommended application size. For Viton® FKM O-ring, append -V to part number (e.g. LMG-12-V).
Typical Applications
- ▸
Industrial Gearboxes & Reducers — Drain/fill port fluid presence and level check - ▸
Hydraulic Power Units (HPU) — Low-point drain monitoring without system shutdown - ▸
Mobile Hydraulics — Construction, agricultural, and mining equipment - ▸
Machine Tool Lubrication Systems — Sump drain plug with visual level confirmation - ▸
Refrigeration & HVAC — Compressor oil sump monitoring (FKM O-ring option) - ▸
Marine & Offshore Equipment — Gearbox drain in corrosive environments (SS option) - ▸
Compressor Crankcases — Oil presence and level verification
Key Advantages Over Standard Drain Plugs
Zero Disassembly Inspection
Check oil level visually at any time — no plug removal, no spill risk, no contamination.
Zero-Leak ORFS Sealing
O-Ring Face Seal eliminates thread-form leak paths. No PTFE tape or pipe compound required.
Direct Drop-In Replacement
Fully interchangeable with SAE J1926 standard ports. No port modification required.
Customizable Material
Brass standard · Stainless steel and carbon steel available on request for corrosive or high-spec environments.
No Calibration Required
Go/no-go red ball indicator is self-explanatory. Maintenance personnel need no specialist training.
Broad Fluid Compatibility
NBR standard for hydraulic/gear oil. FKM (Viton®) option for refrigerants and aggressive chemicals.
Quality & Compliance
| Item | Detail |
|---|---|
| Dimensional Standard | SAE J514 / SAE J1926 |
| Thread Inspection | GO / NO-GO gauging per ASME B1.2 |
| Pressure / Temp Marking | PS 35 bar · MWP 500 psig · max. 80 °C / 175 °F — stamped on glass face |
| Factory Pressure Test | 100% hydrostatic leak test |
| Material Certification | Available on request — EN 10204 2.1 |
Request a Quote or Technical Consultation
OEM quantities · Custom materials · EN 10204 mill certs available on request.
Contact: sophia@js-lumiglas.com |
+86 189 1303 5768
