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The Sekonic ST-50A digital thermohygrograph combines an electronic temperature and humidity display with continuous paper chart recording. View current conditions and retain a physical record for environmental checks.
Discontinued model: Manufacturer sales have ended. Remaining stock, consumables and alternative instruments are subject to availability.
Keep a visible paper history of room conditions with the Sekonic ST-50A temperature and humidity chart recorder. Electronic sensors supply the readings, while separate recording pens trace temperature and relative humidity on a continuous folded chart. The digital display allows staff to check current conditions during routine inspections.
This format suits facilities that retain physical environmental records, including laboratories, storage rooms, manufacturing areas, museums and archive stores.
Sekonic ended manufacturer sales of the ST-50A in April 2026. No direct successor is planned. Please check availability before specifying this model for a new installation.
Sekonic has announced plans to continue consumable sales, including the HEAA temperature and humidity sensor, for approximately seven years after the end of sale. Repair and calibration support are also planned for this period, subject to the work required and available parts.
The ST-50A records on chart paper. SD-card recording belongs to the separate ST-50M model and should not be specified as an ST-50A feature.
| Model | Sekonic ST-50A |
|---|---|
| Sensor types | Semiconductor temperature sensor; polymer capacitive humidity sensor |
| Sensor measurement range | -20 to 80°C; 0 to 100% RH |
| Temperature display accuracy | ±0.5°C from 0 to 50°C |
| Humidity display accuracy | ±3% RH from 20 to 80% RH at 25°C |
| Recorder installation conditions | 0 to 50°C; 20 to 90% RH, without condensation or frost |
| Battery supply | 4 × LR20, 1.5 V alkaline D batteries |
| External power | Optional compatible AC adapter; 9 V DC, 500 mA output |
| Dimensions | 300 × 245 × 105 mm (W × H × D), excluding protrusions |
For existing instruments: These figures follow Sekonic's Japanese catalogue. Earlier export versions may carry different specifications. Refer to the manual supplied with your recorder when confirming accuracy, installation limits or replacement parts. Keep the recorder body within its permitted operating conditions when using a remote sensor.
Keep your Sekonic ST-50A thermohygrograph supplied with the correct chart paper, recording pens and replacement sensor. Quote the relevant part number below when requesting pricing and availability.
| Item | Part number / reference | Description |
|---|---|---|
| Standard chart paper | HE12 / HEGA / HE0140010 | Standard folded recording paper. 5 books per pack. |
| Clean chart paper | HE11 | Clean-paper version for suitable controlled environments. 5 books per pack. |
| Recording pen set | HE13 / HEFA / HEFA15330 | 4 pens per set: 2 red and 2 blue. Red for temperature; blue for humidity. |
| Replacement temperature and humidity sensor | HEAA | Replacement sensor assembly. Provide the recorder serial number and existing sensor details when enquiring. |
| 5 m sensor extension cable | HE04 | Positions the sensor up to 5 m from the recorder. |
| 20 m sensor extension cable | HE05 | Positions the sensor up to 20 m from the recorder. |
| 50 m sensor extension cable | HE06 | Positions the sensor up to 50 m from the recorder. |
| External alarm relay output unit | HE09 | One common alarm output. Requires a compatible AC adapter. |
| AC adapter | Confirm according to supply voltage | Specify the installation's mains voltage and plug type. Confirm the correct adapter reference before ordering. |
Ordering note: Multiple references are shown where our ST-50 series listing uses alternative codes. Please provide the code printed on your existing packaging, particularly for chart paper, so the correct version can be confirmed.
Contact us for pricing and availability. Include the part number, quantity and recorder model. For other replacement parts, attach a photograph of the component and the instrument's serial-number label.
Replacing the Sekonic ST-50A is an opportunity to choose between paper records, electronic data logging and connected environmental monitoring. The following options serve different recording needs and are not direct interchangeable replacements.
| Recording requirement | Alternative | When to consider it |
|---|---|---|
| Paper temperature and humidity records | Sato NSII-Q thermohygrograph | For teams that prefer a visible paper chart and physical records. The NSII-Q uses a rotating drum chart with selectable 1, 7 or 32-day recording periods. Confirm the required temperature range and chart format. |
| Electronic temperature and humidity records | Sato SK-L754 temperature and humidity data logger | For users moving from paper charts to stored readings that can be transferred to a computer for review and analysis. Specify the SK-L754 humidity and temperature model within the SK-L750 series, together with a suitable probe. |
| Connected environmental monitoring | Dickson OCEAView environmental monitoring system | For monitoring multiple rooms, storage areas or equipment through a central system. Compatible wireless loggers and sensors support measurement history and configured alarm notifications. The required hardware, software and notification services depend on the installation. |
Choosing the right option: Specify whether you need paper charts, downloadable readings or remote monitoring with alerts. Include the temperature and humidity ranges, number of monitoring points, sensor locations and any calibration or reporting requirements.
Contact us for pricing and availability. We can help compare a suitable replacement for your existing ST-50A installation.
Contact us for pricing and availability. For consumables, include the item reference and quantity. For an alternative recorder, specify the temperature and humidity ranges, recording period, sensor location and whether you require paper or electronic records.
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The Sekonic ST-50A digital thermohygrograph combines an electronic temperature and humidity display with continuous paper chart recording. View current conditions and retain a physical record for environmental checks.
Discontinued model: Manufacturer sales have ended. Remaining stock, consumables and alternative instruments are subject to availability.
Monitor four measurement points with the Sato SK-L400T 4-channel temperature data logger. Connect Type K thermocouple probes, view all four readings together and record temperature data to an SD card.
Dickson circular chart recorders provide a paper record of temperature, humidity, pressure or external transmitter signals, depending on the model. Select the recorder by measurement type, chart size, recording period and installation requirements.
The Dickson TWP touchscreen data logger displays readings and measurement history on an 8-inch colour screen. Configure it for temperature, humidity or differential pressure monitoring using compatible replaceable sensors.
Palmer Wahl pressure and temperature chart recorders provide a paper record of measurements over time. Choose an 8-inch or 12-inch recorder with an aluminium or Pelican® case, configured for pressure, temperature or combined recording.
Dickson OCEAView™ brings wireless environmental monitoring, alarm notifications and traceable records into one platform. Monitor temperature, humidity and other critical parameters using compatible data loggers and sensors for refrigerators, freezers, laboratories, pharmaceutical storage and cold rooms.
The Isuzu TH27R (TH-27R) thermohygrograph is discontinued. For a replacement temperature and humidity chart recorder, choose the Sato NSII-Q (Sigma II).
The Sato SK-L200THIIα temperature and humidity datalogger is discontinued and has been replaced by the Sato SK-L750 series. For recording both temperature and relative humidity, select the SK-L754 with a suitable probe.
The Evikon E2244 humidity and temperature transmitter measures relative humidity and air temperature for connection to controllers, monitoring instruments and building management systems.
Monnit ALTA Soil Moisture Sensor measures soil moisture tension & soil temperature within the soil. It uses a resistive granular matrix element to accurately measure the matric water potential (soil moisture tension) in the soil and a thermistor based temperature element to measure temperature.
- Safe to use in both hot & freezing temperatures
- Reports matric potential (soil water tension)
- Moisture readings in centibar & kPa
- 0 to 240 centibar (kPA)
- Will not dissolve in soil
- Internally compensated for commonly found salinity levels
- Easy to install and use compared to traditional tensiometers
- Stainless steel electrodes
- No maintenance required
- Temperature readings in C/F.
- 5 ft removable lead
Monnit ALTA® Wireless Thermocouple Sensors leverage Monnit’s award-winning remote monitoring platform to remotely monitor high-temperature applications, such as commercial ovens, kilns, and chimneys. Users benefit from a wireless data transmission range of 1,200+ ft, bank-grade security, and a temperature range of up to 400°C (752°F).
Monnit’s thermocouple is user-programmed to sleep for a specified interval, awake, capture analog data, and then convert this measurement into a temperature. If the sensor captures temperatures outside of user-specified thresholds, an alert is sent via text, email, or call. Monnit’s hardwired thermocouples feature a needle-style probe at the end of a 6’ lead (a K-Type Quick Connect Thermocouple is also available).
The Sato SK-L750 series data loggers record temperature or temperature and humidity for later review on a PC. Choose the SK-L751 for two-channel temperature measurement or the SK-L754 for combined temperature and humidity recording.
The Anritsu AM-9000 series temperature datalogger records measurements across 6 or 12 channels, with fixed thermocouple and multi-input models available. Store readings in internal memory and transfer them to a PC through USB using optional AMS-950 analysis software.
AMS-950 software is sold separately.
The Sekonic ST-50M thermohygrograph records temperature and relative humidity on paper charts and an SD memory card. Its digital display provides local readings, while recorded electronic data can be reviewed on a computer.
Discontinued: The ST-50M is no longer available as a new instrument. This page provides reference information, consumable part numbers and alternative recording options.
The Sato SK-RHC-I temperature and humidity transmitter combines a local display with 4–20 mA outputs for connection to compatible monitoring and control equipment. Three interchangeable probe designs support different sensor positions.
Probe sold separately. An optional AC adapter is available.
Sato compact type thermohygrograph Mini-Cube 7008-00 fits almost anywhere at your convenience.
One box of 7 day charts included.
(Measuring range: -15 to 40°C 5 to 100%)
The Sato NSII-Q Sigma II thermohygrograph records temperature and relative humidity together on a rotating paper chart. Its quartz-driven mechanism provides a visible measurement history for routine environmental checks.
