Sekonic ST-50M Digital Thermohygrograph — Discontinued and Replacement Options
The Sekonic ST-50M has been discontinued. This page is retained to help existing users identify their recorder, check legacy consumable references and select an alternative for temperature and humidity recording.
The ST-50M combined a temperature and humidity display, a continuous paper chart and SD-card data recording. The appropriate replacement depends on whether you need a visible paper record, downloadable electronic readings or a connected monitoring system.
Recommended Alternatives to the ST-50M
These are functional alternatives, not direct replacements with identical features or interchangeable accessories. If you need both an on-site paper trace and electronic records, tell us before selecting a replacement.
| Alternative | Recording method | When to consider it | Main difference from ST-50M |
|---|
| Sato Sigma II NSII-Q |
Temperature and humidity on a rotating paper chart |
Routine visual checks and paper filing |
No SD-card logging; different chart format and consumables. |
| Sato SK-L754 |
Electronic temperature and humidity records, with PC and microSD data transfer |
Local recording, trend analysis and electronic record storage |
No built-in chart printer; requires a compatible SK-L754 probe. |
| Vaisala RFL100 + AP10 with viewLinc |
Networked monitoring, historical records and configurable alarms |
Multiple rooms, warehouses, laboratories and controlled environments |
Requires a configured monitoring system; no built-in paper chart mechanism. |
For Paper Records: Sato Sigma II NSII-Q
The Sigma II is a practical alternative when staff need to inspect and retain a physical temperature and humidity chart. It uses separate pens and a rotating drum, so its recording process differs from the ST-50M's folded chart paper.
- 7210-00: temperature scale −15 to 40°C and humidity scale 0 to 100% RH.
- 7211-00: temperature scale −10 to 50°C and humidity scale 0 to 100% RH.
- Select the correct chart for the recorder model and recording period.
- ST-50M charts, pens and remote sensors are not interchangeable with Sigma II accessories.
View Sato Sigma II thermohygrographs.
For Electronic Records: Sato SK-L754
The SK-L754 records temperature and humidity electronically, with capacity for 16,000 data records. Data can be transferred to a PC or copied to a microSD card, and the dedicated software supports graphing and CSV export.
- SK-L754-1 plug-in probe: −10 to 60°C and 5 to 95% RH.
- SK-L754-2 cabled probe: −20 to 80°C and 5 to 95% RH.
- A compatible probe must be selected separately; check the logger body's ambient limits as well as the probe range.
- The SK-L751 is a temperature-only logger. Choose SK-L754 when humidity must also be recorded.
The SK-L754 has no built-in paper chart printer. Its memory capacity and microSD workflow differ from the ST-50M, so select a recording interval and download schedule suitable for your required retention period.
View Sato SK-L750 Series data loggers.
For Centralised Monitoring: Vaisala viewLinc
For monitoring across several locations, consider Vaisala RFL100 data loggers with suitable humidity and temperature probes, AP10 access points and viewLinc software. The system combines historical records with configurable alarms and reporting.
This is a system upgrade for applications such as pharmaceutical storage, laboratories and controlled rooms. Seacom can help review measurement locations, network coverage, alarm requirements and calibration needs. The logger, probes, access point and software must be specified together.
View Vaisala RFL100, AP10 and viewLinc monitoring options.
What About the Sekonic ST-50A?
The ST-50A is being phased out and is not presented here as the preferred option for a new installation. Do not assume that an ST-50A provides the ST-50M's SD-card recording function. Contact Seacom if your existing procedure specifically requires a Sekonic chart recorder.
Original ST-50M Product Pictures
The following pictures identify the discontinued recorder.
ST-50M Legacy Specifications
Historical specifications are provided for identification and replacement planning. They do not describe the alternative products above.
| Specification | ST-50M legacy reference |
|---|
| Measurements |
Temperature and relative humidity |
| Standard measurement conditions |
−20 to 50°C; 20 to 90% RH, non-condensing |
| With sensor extension cable |
−20 to 80°C; 0 to 100% RH, non-condensing; recorder body must remain within its own operating limits |
| Temperature accuracy |
±1.0°C at 0 to 50°C |
| Humidity accuracy |
±3% RH at 25°C; guaranteed humidity accuracy range 10 to 90% RH |
| Display resolution |
0.1°C and 0.1% RH |
| Chart |
Z-fold paper, 113 mm wide × 12 m long; 100 mm working recording width |
| Memory card |
SD card, 128 MB to 2 GB; SDHC cards of 4 GB or greater are not supported |
| Power |
Four LR20 1.5 V batteries; 9 V DC, 500 mA adapter input |
| Dimensions and weight |
300 W × 245 H × 105 D mm; approximately 2.1 kg without batteries |
Existing ST-50M Charts, Pens and Accessories
These references were listed for the original recorder. Send the existing part number or a photograph for a compatibility and availability check; listing a reference does not confirm current stock.
| Item | Legacy reference | Details |
|---|
| Standard chart paper |
HE12 / HE0140010 / HEGA |
Original listing: 5 pieces per set |
| Clean chart paper |
HE11 |
Original listing: 5 pieces per set |
| Cartridge pens |
HE13 / HEFA15330 / HEFA |
Original listing: 2 red and 2 blue pens per set |
| Sensor extension cable |
HE04 |
5 m |
| Sensor extension cable |
HE05 |
20 m |
| Sensor extension cable |
HE06 |
50 m |
| External control output unit |
HE09 |
Original listing: one common output |
See chart paper and recording consumables and recording pens, ink and ribbons for related enquiries.
Need Help Replacing an ST-50M?
Send Seacom Process Instruments Sdn Bhd your recorder model, temperature and humidity range, measurement location and required recording period. Let us know whether you need paper charts, memory-card downloads, remote alarms or centralised monitoring, and include any existing chart, pen or sensor references you need to retain.
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ST50 Catalogue
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