The Extech SD700 is a room-condition record keeper for pressure, relative humidity, and temperature beside a visible materials inspection. Its value is the dated SD-card trail, not a promise of preservation control or laboratory validation.
What it records beside the bench
The SD700 simultaneously displays barometric pressure, temperature, and relative humidity on its triple LCD, while its datalogger date/time-stamps readings to an SD card in Excel format for transfer to a PC. [1] That makes it a practical companion to a visual inspection: note what was visible, then keep the surrounding room-condition record with the inspection entry rather than treating the meter as a controller.
The current maker page lists selectable sampling at 5, 10, 30, 60, 120, 300, or 600 seconds. [1] The manual also lists AUTO, but the one-second display behavior is not a one-second SD logging mode. [2] For a time-stamped inspection record, choose one fixed interval from that seven-step list and record the start time and setup.
As an Amazon Associate, I earn from qualifying purchases.
Check the Extech SD700 offer on Amazon
Fixed sampling versus AUTO
Fixed sampling is the clearest choice when pressure trend matters. In AUTO, the manual says data are stored whenever the value changes by more than 1% RH or more than 1°C. [2] That is an RH-or-temperature trigger, not a documented pressure-only trigger, so AUTO can leave a pressure change without a new row until RH or temperature crosses its threshold. A fixed 5-, 10-, 30-, 60-, 120-, 300-, or 600-second schedule therefore gives the more legible pressure record.
Choose an interval appropriate to the activity you intend to document; a shorter interval produces more rows, not a validated high-frequency measurement. The datasheet lists those intervals and SD-card Excel logging for PC analysis. [3] These sampling settings do not establish waveform capture or climate control.
What the numbers mean
Use hPa for pressure: the manual gives 10.0–1000.0 hPa at ±2 hPa and 1000.1–1100.0 hPa at ±3 hPa, with 0.1 hPa resolution. [2] Temperature is specified from 0 to 50°C at ±0.8°C with 0.1° resolution. [2] Relative humidity is band-specific: 10–70%RH is ±4%RH, while 70–90%RH is ±(4% of reading + 1%RH), with 0.1%RH resolution. [2] Exactly 70% lies in the overlapping stated ranges; do not invent a sharper boundary.
The datasheet gives a broader RH accuracy formula, but the manual’s conditional bands are the more useful qualification. [2][3] The datasheet and current maker material also print an inHg range as “3248,” while the manual prints “32.48.” [1] [2] Use the hPa specification here rather than interpreting 3248 inHg as a validated operating limit.
Operating limits are not environmental guarantees: the manual specifies 0–50°C operation and less than 90%RH, while the measurement endpoint is listed to 90%RH. [2] The manual’s RF statement is a test condition of less than 3 V/m and below 30 MHz, not achieved accuracy in every installation. [2] No included calibration certificate or NIST/ISO result is established here, and no physical test or certificate purchase is required to use this review.
Card workflow and package limits
Before advanced setup or card removal, stop logging. The manual says the SD card must be at least 1GB, the clock must be correct, and cards formatted by other meters or cameras should not be used; its own formatting procedure erases existing card data. [2] The file structure rolls at 30,000 rows, through HBA folders, with HBA10 described as the final folder, so “Excel workflow” does not mean an infinite single file. [2] The manual describes reading the card with Excel on a computer. This is separate from the optional serial/USB interface and its software; it does not establish supplied spreadsheet licensing or compatibility with every current host.[2]
The maker page lists six AAA batteries, an SD card, Universal AC adapter, and mounting bracket in the package. [1] The older datasheet specifies a 2G card and “20M data,” which is a source-era package/capacity statement, not a tested retention or shipping guarantee. [3] The manual says power is always on with batteries or the AC adaptor because there is no power-off button. [2] It also describes typical battery life of more than one month with new alkaline batteries at 60-second sampling, while faster sampling reduces life. [2]
The buying decision
Buy the SD700 when you need timestamped ambient pressure/RH/temperature samples beside inspection notes and can work with fixed intervals, a manual card workflow, and stated tolerances. Do not buy it as evidence of controlled climate, preservation, sterilization, clinical, food, pharmaceutical, or regulated-audit conditions. The Amazon listing identifies the offered model as the Extech SD700 Barometric Pressure, Humidity, Temperature Datalogger. [4] Confirm the actual package before relying on the older datasheet’s capacity wording.
As an Amazon Associate, I earn from qualifying purchases.
Check the Extech SD700 offer on Amazon
This review uses the current maker page, its eight-physical-page SD700-en-US_v2.8 9/23 manual, the one-page 2/8/12 R1 datasheet, and an ordinary retail page for model identity. Retrieval does not establish the revision in the seller’s carton.