Hydrocarbon dew point and water dew point are two of the contractual numbers that decide whether natural gas is fit to enter a transmission line, a city-gate station or a plant fuel header. Online chilled-mirror and TDLAS analyzers cover continuous custody-transfer duties, but Pakistani pipeline, processing and gas-plant teams also need a portable method for survey work, turnaround checks, disputed readings and stations that do not yet have a permanent analyzer house. That is the job of a manual chilled-mirror field tester.
This note covers portable hydrocarbon and water dew-point testing with the Michell CDP301 Condumax Dew-Point Tester. It explains what the datasheet specifies, how the instrument sits beside online Condumax II and OptiPEAK TDL600 systems, and how to use it safely at pipeline sample points. Instrument figures come from the Michell CDP301 datasheet (CDP301_99994_EN) and the live Tetracon product page. No prices or exclusivity claims are made here.
Why portable HCDP and WDP still matter on Pakistan gas networks
Pakistan’s transmission and distribution network, processing plants and large industrial fuel-gas users write dew-point limits into gas quality agreements for good reason. Liquid dropout fouls regulators, meters, filters and burners; hydrate risk rises when water dew point is too high; and custody-transfer disputes are expensive when two parties disagree on a spot reading. Continuous analyzers answer that need at key nodes, but field teams still face duties that a fixed analyzer cannot cover alone:
- Transmission and lateral checks. Walk a sample point at a valve station, city gate or offtake, take a documented HCDP and WDP reading, and leave without installing a permanent analyzer house.
- Validation of online analyzers. The CDP301 datasheet lists validation of online analyzers as a named application — useful when a Condumax II or OptiPEAK reading is questioned during a turnaround or after a sample-system change.
- Processing and sour gas. Processing plants and sour streams need a hazardous-area capable tester that can sit close to the sample point rather than relying on long, slow sample lines back to a safe-area cabin.
- Sites without a permanent house. Smaller stations, temporary bypasses and construction phases often need contractual dew-point evidence before an online system is commissioned.
Michell CDP301: what the datasheet says
The CDP301 is a manual, visual chilled-mirror dew-point tester for natural gas processing and transmission. Michell positions it as a portable, 21st-century advancement of the Bureau of Mines dew-point tester, extending the Condumax chilled-mirror family with battery power, hazardous-area certification and camera-backed logging. The operator watches condensation form on a cooled mirror, distinguishes water from hydrocarbon dew point visually, and logs temperature and pressure at the frost/condensation point. Cooling rate is controlled to ASTM D1142 or ISO 6327 practice for natural-gas dew-point measurements.
| Specification | CDP301 (datasheet) |
|---|---|
| Measuring technique | Chilled mirror; visual identification of both water and hydrocarbon dew point |
| Sensor cooling | Automated cooling ramp rate selectable to ASTM D1142 or ISO 6327 practice |
| Depression range | Up to ΔT >65 °C (149 °F) |
| Accuracy (mirror surface) | ±0.5 °C (±0.9 °F) |
| Resolution | 0.1 °C / 0.1 °F |
| Sample flow | 0.25 to 0.5 Nl/min |
| Operating pressure | Up to 100 barg (1450 psig) |
| Sample supply pressure | 20 to 100 barg (290 to 1450 psig) |
| Pressure measurement | HCDP and WDP; MPa / barg / psig; resolution 0.1 MPa, 0.1 barg, 1 psig; accuracy ±0.25 %FS |
| Enclosure / IP | Cast LM25 alloy, IP64 (NEMA 4 equivalent) |
| Gas connections | 1/8" NPT |
| Display and camera | 5.7" full-colour display with five push buttons; integral HD camera for still and video of the mirror |
| Onboard storage | 2 GB for logs and images |
| Battery | Rechargeable Li-ion, up to 8 hours from full charge; spare battery can be swapped (charge and replace in a safe area only) |
| Weight | 8 kg (17.6 lb) |
| Ambient | −30 to +50 °C, max 95 %rh |
| Hazardous area | ATEX/UKEX II 2 G Ex db ia IIB+H2 T3 Gb; IECEx Ex db ia IIB+H2 T3 Gb; cQPSus Class I Division 1 / Zone 1 |
| Data transfer | USB Standard B for log/image transfer (safe area only) |
| Mounting | 5/8"–11 UNC tripod thread; optional bench-top mount |
The datasheet also lists natural gas processing, transmission pipeline checking, sour natural gas and validation of online analyzers as application areas. Accessories include a purpose-designed 316 stainless-steel sample system for pressure and flow regulation and contaminant removal, an anti-static rucksack for carrying the unit into the hazardous area, and a wheeled hardcase for road and air transport of the tester plus charger, spare battery and mirror cleaning kit.
How a measurement cycle works
- Connect a conditioned sample. Use the purpose-designed sample system to regulate pressure and flow and remove contaminants. Sample supply is specified at 20–100 barg into an analyzer rated to 100 barg, with flow held between 0.25 and 0.5 Nl/min.
- Cool the mirror under control. Select the ASTM D1142 or ISO 6327 cooling-ramp practice so the rate matches accepted natural-gas dew-point methods.
- Watch water versus hydrocarbon. The colour display and illumination are designed so the operator can see which condensate forms first and identify water and hydrocarbon dew points separately.
- Capture evidence. Press to log temperature and pressure at the frost/condensation point and store still or video images of the mirror. Up to 2 GB of onboard storage holds multiple cycles for later review.
- Transfer in a safe area. USB export of logs and images, and battery charging or spare-battery swap, must be done in a safe area only.
CDP301, Condumax II and OptiPEAK — who does what
| Instrument | Primary job |
|---|---|
| Michell CDP301 | Portable manual chilled-mirror tester for both hydrocarbon and water dew point at the sample point; hazardous-area certified; camera-backed logs for survey, validation and stations without a permanent analyzer. |
| Michell Condumax II | Continuous online Dark Spot chilled-mirror hydrocarbon dew-point analyzer for custody transfer, transmission and processing. See our note on Condumax II and OptiPEAK for Pakistan pipelines. |
| Condumax II Transportable | Same online Condumax measurement principle in a moveable package for multi-site commissioning and temporary duties. |
| Michell OptiPEAK TDL600 | Online TDLAS water-moisture analyzer for natural gas — answers the water clause, not HCDP. Often paired with Condumax II where both parameters are contractual. |
Use the CDP301 when you need a portable, documented HCDP/WDP check. Keep Condumax II (or the Condumax II + OptiPEAK combined system) for permanent online HCDP and TDLAS moisture at custody-transfer and transmission nodes. Do not treat a water-only laser dew-point analyzer as a substitute for hydrocarbon dew point — they answer different contractual questions. For TDLAS water (ppm) measurement alongside H2S and CO2 see also AccuLase-D1; for broader HCDP/WDP context see hydrocarbon and water dew point in natural gas.
Field practice for Pakistan sites
- Stay inside the pressure window. Sample supply is 20–100 barg. Regulate high-pressure take-offs carefully; do not feed the tester from an unregulated tap above the rated supply.
- Heat and sun. Ambient rating is −30 to +50 °C. In summer, shade the unit at open valve stations and avoid leaving it on hot metal decks.
- Hazardous-area discipline. The CDP301 is certified for Zone 1 / Class I Div 1 use near the sample point, but USB transfer and battery charging or replacement must wait until you are in a safe area.
- Sample conditioning. Use the stainless sample system so liquid carry-over and particulates do not foul the mirror; clean the mirror with the supplied kit between campaigns.
- Evidence trail. Keep the timestamped images and logged temperature/pressure with the site report so online-analyzer validation and custody disputes have a clear audit trail.
- Tripod or bench. Use the 5/8"–11 UNC tripod mount at outdoor sample points, or the optional bench-top mount in a sheltered analyzer room.
FAQ
Does the CDP301 measure both hydrocarbon and water dew point?
Yes. The Michell CDP301 datasheet describes a manual chilled-mirror tester for natural gas that supports visual identification of both water and hydrocarbon dew point, with pressure measurements logged for HCDP and WDP.
What accuracy and depression range does the datasheet quote?
Mirror-surface accuracy is ±0.5 °C (±0.9 °F), resolution is 0.1 °C, and the depression range is up to ΔT greater than 65 °C. Sample flow is 0.25 to 0.5 Nl/min at operating pressures up to 100 barg.
Is the CDP301 certified for hazardous areas?
Yes. The datasheet lists ATEX/UKEX II 2 G Ex db ia IIB+H2 T3 Gb, IECEx Ex db ia IIB+H2 T3 Gb, and cQPSus Class I Division 1 / Zone 1 approvals, so the tester can be positioned close to the process sample point.
When should we use CDP301 instead of Condumax II or OptiPEAK?
Use CDP301 for portable survey, turnaround validation and stations without a permanent analyzer. Use Condumax II for continuous online hydrocarbon dew point, and OptiPEAK TDL600 for continuous online TDLAS water moisture. Many custody-transfer sites need both online analyzers plus a portable tester for checks.
Where can Pakistani teams see the product and ask for support?
See the catalogue page for the CDP301, browse moisture and dew point, or contact Tetracon with your sample pressure, whether you need HCDP, WDP or both, and whether the duty is portable survey or online validation.
Next steps
Tetracon supplies gas analysis, moisture and process instrumentation to Pakistan’s industry, transmission and distribution operators, processing plants and laboratories, including Michell Instruments products. Tell us the sample pressure, whether hydrocarbon dew point, water dew point or both must be proven, whether the duty is portable or online, and how results must be recorded. Use the contact page or see our services. Start with the catalogue pages for the CDP301, Condumax II and OptiPEAK TDL600; browse moisture and dew point and gas analysis; or see all Michell Instruments products. Free technical guides are collected under Guides.