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ST50 Catalogue
Digital Thermohygrograph
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Sekonic ST-50A Digital Temperature and Humidity Chart Recorder
The Sekonic ST-50A displays temperature and relative humidity and records both on a continuous paper chart.
- Electronic temperature and humidity sensing with LCD display.
- Optional extension cables for remote sensor placement.
- Battery operation or a suitable external DC supply.
- Desktop or wall-mounted installation.
Being phased out: confirm availability before ordering. Alternatives include the Sato Sigma II for paper records, Sato SK-L754 for electronic logging and Vaisala viewLinc for centralised monitoring.
Sekonic ST-50A Digital Temperature and Humidity Chart Recorder
The Sekonic ST-50A is being phased out. Contact Seacom to confirm availability before ordering a recorder or specifying one for a new installation. Existing users can use this page to identify specifications, consumables and suitable alternatives.
The ST-50A displays temperature and relative humidity electronically and records both on a continuous paper chart. It is designed for indoor environmental recording in laboratories, storage rooms, production areas, museums and similar locations where a visible record is useful.
Key Features
- Simultaneous temperature and humidity display and paper recording.
- Electronic sensing with optional extension cables for remote sensor placement.
- Z-fold chart paper with separate temperature and humidity traces.
- Battery operation or a suitable external DC supply.
- Desktop or wall-mounted installation.
The ST-50A does not provide the ST-50M's SD-card recording function. Choose an electronic data logger or monitoring system if downloadable records are required.
Recommended Alternatives to the ST-50A
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-50A |
|---|---|---|---|
| Sato Sigma II NSII-Q | Temperature and humidity on a rotating paper chart | Routine visual checks and paper filing | Rotating drum rather than folded chart paper; no digital display or remote electronic probe. |
| 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-50A'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-50A 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 replaces the paper-recording workflow with electronic logging. It has no built-in chart printer. 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.
ST-50A Specifications for Existing Installations
The following specifications refer to the ST-50A. Replacement instruments have their own ranges, accuracy specifications and installation requirements.
| Specification | ST-50A 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 |
| Recording method | Paper chart; no ST-50M-style SD-card recorder |
| 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 |
| Sensor types | Semiconductor temperature sensor and capacitive humidity sensor |
| Calibration adjustment | Temperature: one point; humidity: one or two points |
| Mounting | Desktop or wall mounting |
The wider remote-sensor measuring range does not extend the recorder body's permitted ambient range. Keep the recorder within −20 to 50°C and 20 to 90% RH without condensation.
ST-50A Chart Paper, Pens and Accessories
The references below are retained from the existing product listing. Confirm the complete part number, pack quantity, compatibility and supply availability before ordering.
| 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.
ST-50A or ST-50M: Which Model Do You Have?
Check the model label before requesting parts or a replacement. The ST-50A is the paper-chart model; the discontinued ST-50M added SD-card recording and time printing. Similar appearance does not establish identical functions or accessory compatibility.
View ST-50M legacy information and alternatives.
Choosing an ST-50A Alternative
- Paper record: confirm whether a rotating drum chart is acceptable instead of a continuous folded chart.
- Sensor position: tell us if the sensor must be placed away from the recorder. A traditional thermohygrograph does not reproduce the ST-50A's remote electronic sensor arrangement.
- Measurement conditions: provide the required temperature and humidity range, accuracy and calibration requirements.
- Records and alarms: specify whether you need local paper records, downloadable files or a networked system with notifications.
- Existing accessories: include chart, pen and cable references; do not assume they can be reused with another recorder.
Need Help with an ST-50A Recorder?
Contact Seacom Process Instruments Sdn Bhd with your model number, application, measuring range and preferred recording method. For consumables or replacement advice, include photographs of the recorder label and the existing chart, pen or sensor connection.
You might also like
The Sato Thermohygrograph Sigma II NSII-Q continuously records temperature and relative humidity on an easy-to-read paper chart, providing a visible record without requiring a computer or network.
- Temperature ranges of −15 to +40 °C or −10 to +50 °C
- Relative-humidity range from 0 to 100 %RH, non-condensing
- Selectable 1-day, 7-day or 32-day chart rotation
- Transparent cover allows the chart to be viewed while closed
- Battery-powered quartz clock with no external supply required
- Suitable for warehouses, laboratories, clean areas and production rooms
The Sekonic ST-50M digital thermohygrograph is discontinued. It combined temperature and humidity measurement with paper chart recording and SD-card storage.
- Paper records: consider the Sato Sigma II NSII-Q.
- Electronic records: consider the Sato SK-L754 temperature and humidity data logger.
- Centralised monitoring and alarms: consider Vaisala RFL100, AP10 and viewLinc.
Contact Seacom to match the replacement to your recording requirements. Features and accessories differ from the original ST-50M.
16 other products in the same category:
The Sekonic SP-100 is a portable universal 6-channel chart recorder for temperature and process signals.
- Thermocouple, Pt100, DC voltage and 4–20 mA inputs.
- Colour chart recording with configurable ranges and scaling.
- Selectable chart speeds and recording formats.
- Optional memory-card recording.
Discontinued model. Contact Seacom for availability, pricing and configuration details.
The Sato SK-L400T measures and records temperature from up to four Type K thermocouple probes, with all four readings shown on a large backlit display.
- Four temperature channels for comparing multiple measurement points.
- SD-card recording with intervals from 1 second to 90 minutes.
- Independent high and low alarms for each channel.
- MAX/MIN, relative readings and T1–T2 temperature difference.
- Battery operation with an optional AC adapter.
- Probes sold separately; measuring range depends on the selected probe.
The Anritsu AM-8000 Series is discontinued and has been replaced by the AM-9000 Series.
For a replacement, select the appropriate channel count, thermocouple input configuration and recording interval.
- 6-channel and 12-channel replacement options.
- Fixed thermocouple-type or multi-input models.
- USB communication and optional AMS-950 analysis software.
- Confirm existing probe, connector and accessory compatibility.
Dickson round chart recorders provide a visible paper record of temperature or temperature and humidity for routine inspection and filing.
- 3-inch SC3: compact temperature recorder
- 4-inch SL4: temperature recorder with digital display
- 8-inch KT8: temperature recording with sensor and channel options
- 8-inch TH8: temperature and relative humidity recording
- Replacement selection assistance for older KT6, TH6, KT8P, KT856 and TH8P models
Send your existing model number, measurement range and chart reference so we can help identify a suitable configuration.
The Sato SK-L200TH II temperature and humidity data logger is discontinued. The replacement is the Sato SK-L754, selected with a compatible temperature and humidity probe.
- Electronic temperature and humidity recording.
- 16,000 stored readings per channel.
- USB communication and microSD data transfer.
- Choice of plug-in or cabled probe, purchased separately.
The Vaisala VDL200 is a secure Power-over-Ethernet data logger for monitoring temperature, relative humidity, carbon dioxide and analog or Boolean inputs in controlled and GxP-regulated environments.
Designed for the Vaisala viewLinc Continuous Monitoring System, the VDL200 combines interchangeable smart probes, onboard memory and battery backup to provide reliable, gap-free environmental monitoring.
The Isuzu TH27R paper temperature and humidity recorder has been discontinued and is no longer recommended for new installations. Seacom continues to support existing instruments with selected chart papers and recording pens.
- Legacy temperature range from −20 to +50 °C
- Relative-humidity range from 0 to 100 %RH
- Quartz-driven cylindrical paper-chart recorder
- Replacement TH27R chart papers and cartridge pens remain available
- Existing recorder and chart details must be confirmed before ordering
- Closest current substitute: Sato Sigma II NSII-Q thermohygrograph
The Anritsu AM-9000 Series records temperature from six or twelve thermocouple channels in one portable instrument. Choose a fixed thermocouple-type model or a flexible multi-input model for temperature and DC-voltage measurement.
- Choice of 6-channel or 12-channel instruments
- Fixed thermocouple-type and multi-input versions
- Supports E, K, J, T and R thermocouples according to model
- 120,000 measurement-data memory
- USB 2.0 Micro-B communication for data transfer
- Battery operation or optional AC adaptor
- Optional AMS-950 software for PC analysis
DeltaTrak in-transit temperature loggers and recorders document temperature conditions during shipment.
- 16000 Series: disposable paper chart recorders with model-dependent recording periods from 5 to 90 days.
- FlashLink Mini PDF: single-use electronic logger with USB PDF and CSV reports.
- Choose according to shipment duration, temperature range and the receiving team's record requirements.
The Sato Thermohygrograph Sigma II NSII-Q continuously records temperature and relative humidity on an easy-to-read paper chart, providing a visible record without requiring a computer or network.
- Temperature ranges of −15 to +40 °C or −10 to +50 °C
- Relative-humidity range from 0 to 100 %RH, non-condensing
- Selectable 1-day, 7-day or 32-day chart rotation
- Transparent cover allows the chart to be viewed while closed
- Battery-powered quartz clock with no external supply required
- Suitable for warehouses, laboratories, clean areas and production rooms
The Sato SK-L750 Series provides portable, configurable recording for temperature or temperature and humidity, with interchangeable probes, local display, USB communication and microSD data transfer.
- SK-L751: two-channel temperature data logger
- SK-L754: one temperature and one relative-humidity channel
- 16,000 stored readings per channel
- Four recording modes and 14 selectable logging intervals
- USB real-time monitoring and CSV data export
- AA-battery operation with optional AC-adapter power
The Vaisala DL2000 combines precision temperature and relative-humidity monitoring with optional analog or door-contact inputs for viewLinc systems.
- Scheduled for future discontinuation; confirm availability before specifying
- Current replacement platform: Vaisala VDL200 with suitable smart probes
- Internal temperature and relative-humidity measurement
- Optional current, voltage or Boolean input configurations
- Onboard memory and a typical 10-year battery life
The DicksonOne TWP provides local touchscreen viewing and cloud-connected monitoring of temperature, relative humidity or differential pressure. Its replaceable sensor system simplifies calibration and supports different monitoring applications using the same logger platform.
- Large 8-inch LCD touchscreen
- WiFi, Ethernet and Power over Ethernet connectivity
- Approximately 1,000,000 sample-point backup capacity
- Up to 70 hours of rechargeable battery backup
- Replaceable temperature, humidity, thermocouple, RTD and differential-pressure sensors
- Phone, text and email alarms through a DicksonOne subscription
The Sekonic ST-50M digital thermohygrograph is discontinued. It combined temperature and humidity measurement with paper chart recording and SD-card storage.
- Paper records: consider the Sato Sigma II NSII-Q.
- Electronic records: consider the Sato SK-L754 temperature and humidity data logger.
- Centralised monitoring and alarms: consider Vaisala RFL100, AP10 and viewLinc.
Contact Seacom to match the replacement to your recording requirements. Features and accessories differ from the original ST-50M.
The Vaisala RFL100 uses secure, long-range VaiNet wireless technology to monitor temperature, relative humidity and carbon dioxide with the AP10 Access Point and viewLinc Continuous Monitoring System.
- At least 50 m typical indoor wireless range
- Up to 32 RFL100 data loggers per AP10
- 30 days of local measurement memory
- Approximately 18 months of battery operation for temperature and humidity monitoring
The Sato Mini-Alpha 7006-00 is a compact thermohygrograph that records temperature and relative humidity on a seven-day paper chart.
- Temperature range: −15 to 50°C.
- Humidity range: 10–100% RH.
- Quartz drum drive powered by one AA battery.
- Desktop or wall-mounted use; approximately 0.8 kg.
- Replaceable chart paper and cartridge pens.