The CA202 144-202-000-203 piezoelectric accelerometer is widely used in rotating machinery protection and condition monitoring across oil and gas, power generation, and heavy industry. When installing this sensor on a bearing housing, gearbox, or turbine casing, one of the earliest and most critical decisions is the mounting technique. The choice between magnetic and adhesive mounting directly affects measurement frequency response, installation repeatability, maintenance convenience, and long‑term reliability. This article compares the two methods from a practical field‑service perspective, helping engineers and reliability teams select the approach that best preserves the CA202’s specification while matching site constraints.
Why Mounting Method Matters for Piezoelectric Accelerometers
A piezoelectric accelerometer generates charge proportional to the acceleration it experiences. The mechanical coupling between the sensor base and the machine surface forms a spring‑mass system. Any compliance introduced by the mounting layer becomes a mechanical filter, altering the accelerometer’s natural resonance and high‑frequency response. For the CA202, which is typically used to detect unbalance, misalignment, bearing defects, and gear mesh faults, a mounting method that reduces the usable bandwidth too much can mask early fault signatures.
Poor mounting also introduces amplitude errors, phase shifts, and noise, undermining the trustworthiness of vibration data. At the same time, mounting must be practical: a permanent epoxy bond may deliver the widest frequency range, but it might be prohibitive if the sensor must be moved regularly for route‑based monitoring.
Magnetic Mounting: Speed and Portability
A magnet base screws onto the CA202’s mounting stud and attaches to a flat ferromagnetic surface. Because no tool, curing time, or surface preparation beyond cleaning is required, this method is the default choice for many walk‑around data collection programs.
Typical magnetic mounts consist of a rare‑earth magnet inside a steel housing, often with a protective plastic ring to avoid scratching machine surfaces. A high‑pull magnet rated for 20‑kg holding force or more can keep the sensor stable on most horizontally mounted equipment.
Advantages observed in the field:
– Fast exchange between measurement points – a single CA202 can serve dozens of bearings in one route.
– No consumables – reduces recurring cost compared to adhesive kits.
– Easily removed after measurement – leaves no residue on the machine casing.
Limitations:
– Additional mass between the sensor and the machine lowers the mounted resonance. A practical magnetic mounting usually limits the usable frequency range to 2 kHz or 3 kHz, depending on the magnet size, surface finish, and sensor mass. This is sufficient for general rotating machinery monitoring but may miss high‑frequency bearing‑defect harmonics.
– Surface curvature or roughness reduces contact area and introduces rocking motion, causing amplitude errors.
– The magnet can collect metallic debris, which may degrade contact integrity over multiple installations.
– On vertical or overhead surfaces, vibration or shock could dislodge the magnet if the holding force is marginal.
For the CA202 144-202-000-203, which has a useful response beyond 10 kHz when stud‑mounted, a magnetic mount will roll off the amplitude above roughly 3–4 kHz. In practice, engineers frequently accept this trade‑off for the convenience of rapid data collection on electric motors, pumps, and fans where primary fault frequencies are well below 2 kHz.
Adhesive Mounting: Near‑Stud Performance with Flexibility
Adhesive mounting uses a thin layer of bonding agent—cyanoacrylate, two‑part epoxy, or specialised mounting wax—between the sensor base and the machine surface. The hardened adhesive eliminates the air gap and the compliance of a magnet, producing a coupling stiffness much closer to that of a threaded stud.
There are three common adhesive types in industrial monitoring:
– Cyanoacrylate (instant adhesive) – Cures in seconds, provides excellent stiffness and wide‑band response. Best for smooth, clean surfaces. Temperature limit usually around 100 °C.
– Two‑part epoxy – Offers higher temperature tolerance (up to 150 °C or more) and fills minor surface imperfections. Requires mixing and curing time.
– Double‑sided mounting tape or wax – Quick and clean, but suitable only for low‑frequency applications (below 500 Hz) due to low stiffness. Rarely recommended for critical machinery.
With a properly applied adhesive pad, the CA202 can achieve its full specified frequency range, making it possible to track early‑stage rolling‑element bearing defects and gear‑mesh sidebands that appear above 5 kHz.
Advantages:
– Preserves high‑frequency response – adhesive coupling can extend the flat response region to 10 kHz or higher, depending on the adhesive thickness.
– Works on non‑magnetic surfaces such as aluminium or stainless‑steel housings.
– Less sensitive to surface curvature if a filler epoxy is used.
– Stable on vertical and inclined surfaces; no risk of magnet dislodgement.
Limitations:
– Permanent or semi‑permanent – removing a cured epoxy‑bonded sensor often requires a solvent or mechanical force, which can damage the accelerometer if not done carefully.
– Cyanoacrylate residues must be scraped off, and repeated applications build up uneven layers.
– Curing time delays immediate data collection; even instant adhesives need a few seconds to set.
– Adhesive degrades in certain chemical environments and high humidity unless specifically chosen.
Direct Performance Comparison
| Parameter | Magnetic Mounting | Adhesive Mounting |
|---|---|---|
| Typical usable frequency range (CA202) | 2 Hz – 3 kHz | 1 Hz – 10 kHz |
| Mounted resonance | 7–10 kHz | >25 kHz |
| Installation time | 5 seconds | 10–60 seconds (+ curing if epoxy) |
| Removability | Immediate, reusable | Permanent or residue removal needed |
| Surface requirements | Flat, clean ferromagnetic | Flat, clean (material independent) |
| Temperature limits | Limited by magnet (typically 120 °C) | Epoxy up to 150 °C, cyanoacrylate ~100 °C |
| Recurring cost | None | Adhesive consumables |
| Risk to sensor during removal | Low | Medium (bond breaking can damage case) |
| Suitability for route‑based monitoring | Excellent | Poor |
| Suitability for permanent online monitoring | Acceptable if magnet secured | Preferred |
How to Choose the Right Mounting for Your Application
Consider the following factors when mounting CA202 144-202-000-203 sensors:
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Frequency range of interest. If you are monitoring general rotating equipment with dominant fault frequencies below 2 kHz (e.g., pump impeller vane pass, fan blade pass), magnetic mounting is adequate. For gearbox and rolling‑element bearing condition monitoring where high frequencies up to 10 kHz are relevant, use adhesive mounting.
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Surface material and shape. On cast‑iron pump casings or mild‑steel motor frames, magnetic mounting works well. On stainless‑steel, aluminium, or non‑magnetic alloy housings, adhesive becomes necessary. If the surface is curved, a thin adhesive layer can conform without loosening, whereas a rigid magnetic base may rock.
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Maintenance access and monitoring strategy. Walk‑around programs with a portable data collector favour magnetic mounts. If you are installing the CA202 for permanent online monitoring, adhesive (especially epoxy) offers long‑term stability without the risk of a magnet being knocked off during routine cleaning or maintenance.
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Temperature exposure. In gas turbine exhaust casings or high‑temperature pump bearings, ensure the adhesive or magnet can withstand the surface temperature. At ambient conditions beyond 120 °C, only special high‑temperature epoxy or stud mounting should be considered.
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Safety and mechanical stability. On overhead or vertical surfaces, rely on adhesive or mechanical studs. A sudden loss of magnetic grip can damage the sensor and create a foreign‑object risk.
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Data trend repeatability. When comparing vibration spectra over months, mounting repeatability matters. Magnetic mounts placed on exactly the same spot with a reference mark can produce reproducible results. Adhesive pads, once applied, are consistent but cannot be reused. For route‑based trending, standardise the magnet placement point and mark it.
Mounting Best Practices to Preserve CA202 Accuracy
Regardless of the method you choose, the success of vibration measurement hinges on installation discipline:
- Surface preparation. Remove paint, rust, and oil from the contact area. A smooth machined surface with a roughness better than Ra 3.2 µm provides the best stiffness. For magnetic mounting, a thin layer of high‑vacuum grease improves high‑frequency transmission and prevents fretting corrosion.
- Tightening torque for magnetic bases. Finger‑tighten the base onto the sensor stud, then use a spanner to apply the manufacturer’s recommended torque (typically 2–3 N·m). Over‑torque will strip the stud or damage the piezoelectric element.
- Adhesive thickness. Keep the adhesive layer as thin as physically possible. A 0.05 mm cyanoacrylate bond delivers far better frequency response than a 0.5 mm thick pad. Use a single drop and press firmly until set.
- Check cable strain relief. Route the CA202’s coaxial cable so that its weight does not pull on the sensor body. Use cable ties and a service loop to avoid microphony‑induced noise.
- Validate frequency response post‑installation. After mounting, tap‑test the sensor and compare the spectrum with a known reference. A significant resonance shift or loss of high‑frequency energy indicates a mounting problem.
Frequently Asked Questions
Q: Does magnetic mounting reduce the CA202’s sensitivity?
Not at low frequencies. At frequencies above 1 kHz, the magnet introduces a slight attenuation, but the sensitivity (mV/g) at reference frequencies (e.g., 100 Hz) remains unaffected. The mounted resonance frequency drops, which limits the upper end of the flat amplitude range.
Q: Can I use adhesive on a painted surface?
Avoid it. Paint acts as a spring layer and drastically reduces stiffness, pushing the usable frequency down to 500 Hz or less. Remove the paint down to bare metal before bonding.
Q: How do I remove a CA202 bonded with epoxy?
Gently warm the joint with a heat gun to soften the epoxy, then use a plastic wedge. Do not twist the sensor body, as this can damage the internal crystal stack. Solvents are generally not recommended because they may attack the sensor’s sealing and cable.
Q: What adhesive type is recommended for the CA202?
For temporary tests, methyl‑cyanoacrylate (super glue) works well. For permanent installations, two‑part industrial epoxy rated for the machine’s temperature. Always confirm the adhesive’s compatibility with the sensor’s stainless‑steel case and the machine base material to avoid galvanic corrosion.
Final Recommendation for Field Engineers
Magnetic mounting offers the fastest and most adaptable solution for route‑based machinery health checks with the CA202 144-202-000-203. Adhesive mounting unlocks the sensor’s full diagnostic bandwidth and is the correct choice for permanent online protection systems where high‑frequency fault detection is essential. In many plants, a hybrid strategy is used: a small pool of CA202 sensors is cycled across non‑critical machines with magnetic mounts, while a dedicated set is adhesively installed on critical turbo‑generators, compressors, and gearboxes.
When you need reliable accelerometers, mounting accessories, or support in selecting the correct spare parts for your condition monitoring system, our team at Joyoung Industrial Automation Parts can help. We maintain an extensive inventory of CA202 sensors, compatible cables, magnetic bases, and adhesive kits. For more in‑depth guidance on sensor installation and vibration monitoring, you may also find our articles on Proximity Probe selection and Epro PR6424 replacement specs useful. We also cover industrial I/O module types and GE Mark VI analog I/O sourcing for complete system integration.
Contact us at [email protected] or call +86-181-5013-7565 to discuss your vibration sensor requirements and to arrange technical support and fast delivery worldwide.
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