Description
Product Introduction
The Metrix 5485C-007-020 is a rugged, self-generating moving-coil velocity sensor designed specifically for extreme thermal environments up to 375^\circC (707^\circF). Engineered for direct case-mounting on heavy industrial machinery—including gas turbines, boiler feed pumps, and hot gas expanders—it measures structural casing vibration without requiring external excitation power.
Unlike standard piezoelectric accelerometers that degrade rapidly when exposed to high ambient heat or require delicate charge amplifiers, the 5485C uses a low-impedance coil suspended in a permanent magnetic field. The specific -007-020 configuration designates a factory-calibrated sensitivity of 145 mV/in/sec with a 20-foot stainless steel armored integral cable, ensuring high signal-to-noise performance across long wiring runs in harsh plants.
Key Technical Specifications
| Parameter | Specification |
| Sensitivity Standard | 145 mV/in/sec \pm 5\% (5.71 mV/mm/sec) at 100 Hz |
| Frequency Response | 15 Hz to 2000 Hz (\pm 8\%) |
| Operating Temperature Range | -54^\circC to +375^\circC (Sensor Head) |
| Cross-Axis Sensitivity | Less than 10\% maximum |
| Max Motion Peak-to-Peak | 0.10 inches (2.54 mm) displacement limit |
| Output Impedance | Nominal 550 \ \Omega at 25^\circC |
| Cable Configuration (-020) | 20 Feet (6.1 m) Stainless Steel Interlock Armor Cable |
| Case Material & Mounting | 300 Series Stainless Steel, 4-bolt Flange Mount |
| Hazardous Area Approvals | Class I, Div 1 / Zone 0 Intrinsically Safe (ATEX / IECEx / CSA) |
Application Scenarios & The “Trench” Experience
When an unmonitored exhaust bearing housing on an industrial frame gas turbine experiences a thermal wipe, you don’t just replace a bearing—you replace rotor blading. In one field emergency at a combined-cycle power plant, an old piezoelectric sensor baked out its internal crystal, sending false zero-vibration readings while the turbine housing was shaking at dangerous levels. Installing a pre-tested Metrix 5485C-007-020 restored actual casing velocity metrics back to the DCS panel, catching a thermal expansion binding issue before it ruined the main shaft seals.
- Frame-Type Industrial Gas Turbines – Mounting directly onto turbine exhaust frames and combustor transition housings where temperatures exceed 300^\circC.
- Petrochemical Hot Gas Expanders – Measuring structural vibration on high-temperature flue gas recovery units in fluid catalytic cracking (FCC) plants.
- Boiler Feedwater & Furnace Draft Fans – Providing reliable velocity feedback on severe-duty induction fans operating in dirty, high-ambient draft ducts.
Transparency SOP: Quality Assurance & Testing
We don’t just ship boxes; we test them on actual shaker tables. Every 5485C-007-020 sensor passes our strict 5-step bench verification process before leaving our facility:
- Inbound & Armor Sheath Inspection: Visual check of the stainless steel outer armor for crushes, unraveling, or crimp strain-relief damage at the sensor entry gland.
- Coil Resistance & Isolation Check: DMM measurement of internal coil resistance (verifying target \sim 550 \ \Omega) and Megger testing at 500VDC to confirm coil-to-case isolation (>100 M\Omega).
- Dynamic Shaker Table Sweep: Sensor is mounted to a calibrated vibration exciter at 100 Hz (1.0 in/sec PK) to verify exact 145 mV/in/sec output signal amplitude.
- Transverse & Orientation Audit: Axis sensitivity verified to ensure internal spring assembly is centered and not hanging up when positioned vertically or horizontally.
- Clean & ESD Safe Packaging: Armor cable is re-coiled smoothly without exceeding minimum bend radius, terminals are capped, and the unit is wrapped in protective foam.
5485C-007-020
5485C-007-020
The Veteran’s Tech Trap Guide (Crucial Value-Add)
- ⚠️ Mind the Orientation Sensitive Springs: Moving-coil velocity transducers rely on internal suspension springs. Ensure you know whether your target point requires a vertical or horizontal calibration orientation. Mounting a vertical-only model horizontally will cause the coil to drag against the magnet core, distorting your vibration wave!
- ❗ Never Exceed the Maximum Bend Radius on the Armor: The 20-foot integral armored cable is tough, but forcing a tight bend radius (under 2 inches) right at the sensor gland will kink the inner conductors. Once those conductors short against the outer braid, you get high-frequency noise spikes that look like bearing failure.
- ⚠️ Do Not Pull Cable to Position the Sensor: Always secure the sensor body using its 4-bolt mounting flange first, then route the armored cable. Twisting the sensor by turning the armored cable will twist the internal lead wires and destroy the hermetic seal at the wire entry point.
Frequently Asked Questions (FAQ for Conversion)
Q: Does the Metrix 5485C-007-020 require external DC power?
A: No. The 5485C is a self-generating electrodynamic velocity sensor. It generates its own AC millivolt voltage proportional to vibration velocity directly across its two output wires.
Q: What does the suffix “-007-020” mean in this part number?
A: In Metrix nomenclature, -007 designates the standard sensitivity option (145 mV/in/sec with high-temp internal construction), and -020 specifies 20 feet of integral stainless steel armored cable.
Q: Can I cut or splice the 20-foot integral armored cable?
A: Splicing in high-temperature zones is strongly discouraged because standard terminal boxes cannot handle the heat. Run the full 20 feet of armor outside the hot zone into a suitable junction box before transitioning to standard field cable.
Q: What condition are these surplus 5485C units in?
A: We stock both factory-sealed New Surplus units and fully reconditioned, shaker-tested surplus sensors. Every single unit undergoes physical and electrical validation prior to shipment.
Q: What is the warranty coverage on this sensor?
A: Every Metrix 5485C-007-020 sensor includes a comprehensive 12-month operational warranty. If it fails under normal operating conditions within 12 months of purchase, we replace it immediately.
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