Flow Control
R-8M-75-1
Brooks Instrument Size 8 75 mm Borosilicate Metering Tube
About this part
Brooks Instrument R-8M-75-1 is a heavy-wall, precision-bore borosilicate glass metering tube for size-8 variable-area flowmeters with a nominal 75 mm scale. Brooks documents it in legacy Model 1305F, Sho-Rate 1358F, and GT1600 075-high-flow configurations. Flow range, scale, accuracy, pressure rating, seals, and fittings are properties of the complete meter configuration and matched float, not of the bare tube number alone
Configurations vary. Verify the exact unit before choosing a replacement.
Key Facts
Specifications
| Manufacturer | Brooks Instrument |
| Part number | R-8M-75-1 |
| Component type | Tapered glass variable-area flowmeter metering tube |
| Metering-tube material | Heavy-wall, precision-bore borosilicate glass |
| Documented meter size | Size 8 |
| Nominal scale length | 75 mm (3 in) |
| Documented meter platforms | Legacy Model 1305F, Sho-Rate 1358F, and GT1600 075-high-flow configurations |
| Matched-float requirement | Capacity and scale depend on the specified float and complete meter configuration |
| Accuracy options with this tube | ±10% or ±5% of full scale; ±2%, ±1%, and VDI/VDE accuracy selections are not documented for R-8M-75-1 |
| Repeatability | ≤0.5% of full scale for the complete configured meter |
| Standard accuracy | ±10% of full scale for the complete configured meter |
| Repeatability | 0.5% of full scale for the complete configured meter |
| Rangeability | 10:1 for the complete configured meter |
| Flow accuracy | Standard ±10% of full scale; optional ±5% of full scale |
| Repeatability | 1% of full scale for the complete configured meter |
What Does R-8M-75-1 Mean?
Brooks treats R-8M-75-1 as the complete tube identifier. The manufacturer documents map that identifier into meter ordering codes but do not decode its internal characters individually.
| Segment | Field | Interpretation |
|---|---|---|
| R-8M-75-1 | Brooks tube identifier | Indivisible manufacturer identifier for the documented size-8, nominal 75 mm borosilicate metering tube; its internal characters are not separately decoded in the cited documents. |
| 1358F position VI: 1 | Sho-Rate 1358 tube option | Selects R-8M-75-1; option 2 selects the CRN version. |
| 1305F positions VI–VII: J1 | Legacy Model 1305 tube designator | Selects meter size 8 with R-8M-75-1; J4 is the corresponding CRN selection. |
| GT1600 maximum-flow code: P | GT1600 075-high-flow tube selection | Identifies R-8M-75-1; the second character C, F, J, M, or Q selects the matched float and capacity. |
Documented Tube/Float Capacity Matrix
These are complete-meter full-scale capacities for documented tube/float pairings. Air values use the reference conditions stated for each platform, generally 70°F and 14.7 psia. They must not be asserted as fixed properties of the tube alone.
| Meter platform | Matched float | Water full scale | Air full scale |
|---|---|---|---|
| GT1600 075 high flow | 8-XV-8-A | 0.82 GPM / 180 l/h | 3.3 SCFM / 5.6 m³n/h |
| GT1600 075 high flow | 8-RJ-10 | 1.5 GPM / 340 l/h | 6.3 SCFM / 10 m³n/h |
| GT1600 075 high flow | 8-RJ-23 | 2.4 GPM / 540 l/h | 9.9 SCFM / 16 m³n/h |
| GT1600 075 high flow | 8-RJ-30 | 3.1 GPM / 710 l/h | 13 SCFM / 22 m³n/h |
| GT1600 075 high flow | 8-RJ-39 | 4.7 GPM / 1000 l/h | Not available |
| Sho-Rate 1358 | 8-RV-8 | 0.8 GPM | 3.4 SCFM |
| Sho-Rate 1358 | 8-RJ-10 | 1.5 GPM | 6.0 SCFM |
| Sho-Rate 1358 | 8-RJ-23 | 2.5 GPM | 12.0 SCFM |
| Sho-Rate 1358 | 8-RJ-30 | 3.5 GPM | 15.0 SCFM |
| Sho-Rate 1358 | 8-RJ-39 | 5.0 GPM | Not listed |
| Legacy Model 1305 | 8-RV-8 | 0.8 GPM | 3.0 SCFM |
| Legacy Model 1305 | 8-RJ-10 | 1.5 GPM | 6.0 SCFM |
| Legacy Model 1305 | 8-RJ-23 | 2.5 GPM | 10.0 SCFM |
| Legacy Model 1305 | 8-RJ-30 | 3.5 GPM | 14.0 SCFM |
| Legacy Model 1305 | 8-RJ-39 | 5.0 GPM | Not listed |
Platform-Specific Complete-Meter Ratings
Pressure, temperature, connection, and metrology limits differ by housing platform and certification. Verify the complete meter model before applying any rating.
| Platform | Pressure and temperature rating | Connection context | Metrology context |
|---|---|---|---|
| Legacy Model 1305F, size 8 | 200 psig / 13.8 bar maximum at 250°F / 121°C; CRN version 145 psig / 10 bar | Female 1/2-inch NPT; vertical inlet and outlet | ±10% FS standard, ±5% FS optional; 1% FS repeatability |
| Sho-Rate 1358 | 200 psig from 33–250°F / 1–121°C; CRN version 100 psig over the same range | Standard horizontal female 3/8-inch NPT adaptors; options vary by model code | ±10% FS standard; 0.5% FS repeatability; 10:1 rangeability |
| GT1600, size 08 | 250 psi / 17 bar with threaded connections or 240 psi / 16.5 bar with flanged connections; fluid 33–250°F / 1–121°C | Threaded or flanged orientations depend on complete model code | R-8M-75-1 permits ±10% or ±5% FS configurations; repeatability ≤0.5% FS |
Replacement and Retrofit Boundary
Do not select a replacement solely from the R-8M-75-1 marking. Match the meter platform, serial number, float, scale or calibration, float stops, packing, O-rings, fittings, and certification. Brooks lists Model 1358 replacement tubes and detachable scales by serial number. GT1600 meters can be configured to retrofit GT130x installations, but retrofit dimensions and connection codes must be selected as part of the complete GT1600 configuration.
Safety and Service Notes
- Keep the protective sleeve over the glass tube and fasten the meter window securely.
- Avoid pressure and flow surges, and never service the meter while pressurized.
- For proper operation, legacy Model 1305 and Sho-Rate 1358 meters must be mounted within 6 degrees of true vertical, with flow entering at the bottom.
- Drain an isolated liquid meter to prevent thermal-expansion rupture.
- Brooks warns against glass-tube service with toxic fluids or fluids that react with glass, including steam, alkalis, fluorine, hydrofluoric acid, molten metal, and water above 140°F / 60°C.
- A damaged or mismatched float affects accuracy; use Brooks-specified replacement components and compatible seal materials.
Documentation Downloads
Local PDF copiesPart Photos
5 imagesHistorical archive images for identification, labels, connectors, and condition reference, not current inventory.
Historical Listings & Prices
Historical listing data, not a current offerThe typical recorded price range is $449.99 to $449.99. Based on 1 archived listing record; not a current offer, appraisal, or confirmed sale price.
View archived listing titles
- Brooks 1305D08A1B1A R-8M-75-1 Glass Tube Variable Area Flowmeter 0.6-6 SCFM Air