If a measurement record contains only a date and “normal,” the next person cannot easily establish which space and location were tested with which instrument. Even instrument data logs provide insufficient context without the work changes and purpose of measurement.
Portable gas detector confined-space records must link time, location, instrument number, tester, work status, actual readings and actions. The following operating forms can be adapted into site documents. They are not statutory forms or entry permits; filling every field does not automatically establish work safety or compliance.
1. Separate measurement records and entry judgments into different fields
The tester records instrument condition, measurement conditions and displayed values. The person deciding whether to start or resume work also reviews isolation, ventilation, access control and emergency readiness. Even if one person performs both roles, separate measurement results from the overall judgment in documentation.
US OSHA sample permits combine results with responsibilities, isolation, ventilation, communication and rescue preparation. This article takes the principle that measurements alone do not approve the whole task, without converting those forms or values into Korean requirements. OSHA sample permits
At the top, provide linked permit and risk-assessment document numbers. If none exist, first establish a linking method within site documentation. Recheck equipment identity to prevent attachment of a measurement sheet to another tank or manhole's permit.
2. Form A: basic site and instrument information
Copy the table into a document or spreadsheet and complete its fields. Record names and contact details only as needed for work; exclude unnecessary personal information from public posts or external sharing copies.
Item | Entry | Completion guidance |
|---|---|---|
Record number and revision | __________ | Identify records belonging to the same job |
Work date and site | __________ | Date and precise facility location |
Equipment type and ID | __________ | Compare physical manhole, tank or other number |
Task and scope | __________ | Distinguish external and internal work |
Linked document numbers | __________ | Risk assessment, work permit and other records |
Measurement purpose | __________ | Initial verification, during work, after changes, etc. |
Expected gases and evaluation basis | __________ | Contents, process, substance information, etc. |
Unmeasured items and reasons | __________ | Distinguish absent sensors, inaccessible locations, etc. |
Instrument model and number | __________ | Link asset and serial numbers |
Installed sensors and units | __________ | Verify display units for each gas |
Inspection and calibration history links | __________ | Related record numbers and check results |
Sampling configuration | __________ | Diffusion or remote sampling, hose, filters, etc. |
Tester and reviewer | __________ | Distinguish personnel by role |
Source of decision criteria | __________ | Document name, version and approving authority |
Instead of simply “calibration completed,” link the specific instrument and record reviewed. Function checks such as bump tests and calibration have different purposes and should not share a single check. Verify intervals and procedures using model instructions and the site plan.
When entering criteria, do not assume instrument alarm settings, site decision criteria and legal exposure limits are the same numbers. Mixing criteria with different purposes can distort even the comparison of instantaneous readings. This form contains no preprinted universal limits.
3. Form B: actual results by location
Record oxygen in the instrument's units, such as percent by volume, and toxic gases in the corresponding sensor units. Verify whether combustible readings are percentage of the lower explosive limit (%LEL) or another indication. Assign one point and time to each row, adding gases to match site targets.
Measurement confirmation time | Point ID, depth and direction | Work and ventilation status | O₂(unit:___) | Combustible(unit:___) | Gas:___(unit:___) | Gas:___(unit:___) | Instrument condition and tester |
|---|---|---|---|---|---|---|---|
__________ | __________ | __________ | __________ | __________ | __________ | __________ | __________ |
__________ | __________ | __________ | __________ | __________ | __________ | __________ | __________ |
__________ | __________ | __________ | __________ | __________ | __________ | __________ | __________ |
__________ | __________ | __________ | __________ | __________ | __________ | __________ | __________ |
For remote sampling, describe the hose-tip position, not the instrument body's location. Define a method for recording values after transport and response are verified following movement. See OSHA atmospheric testing procedures for the principle of considering instrument response time.
Do not fill an unavailable value with a blank or 0. Distinguish “no sensor,” “flow fault,” “overrange indication” and “location inaccessible,” linking actions. 0 is an instrument indication; unmeasured means information was not obtained. They are not interchangeable.
4. Form C: changes, alarms and actions
This section records events after initial testing. Include ventilation stoppage, process changes, sludge movement, piping changes, worker movement and instrument replacement as applicable. Changed evaluation conditions can warrant records without an alarm.
Event time | Change or abnormality | Stop, evacuation and control actions | Follow-up measurement or document number | Reviewer and restart decision |
|---|---|---|---|---|
__________ | __________ | __________ | __________ | __________ |
__________ | __________ | __________ | __________ | __________ |
__________ | __________ | __________ | __________ | __________ |
On concentration alarms or abnormalities, stopping and evacuation under site procedures take priority. Do not stay in a hazardous area to complete a record. When filling missing events afterward from safety, distinguish actual event time and later entry time.
For restart, briefly state the cause, controls and evidence reviewed, rather than “normal.” If conditions remain incomplete, record “work held” and a follow-up owner. See the HSE confined-space safety guide for preparation principles, then make them specific in site procedures.
5. Hypothetical entry: a measurement row with an instrument fault
The following hypothetical example demonstrates entries without numerical readings. Suppose a flow fault occurs while remotely sampling point B in tank T-03. Enter “valid measurement unavailable” for gas values and describe the fault in instrument status. Do not copy the next point's values or retain the previous readings.
The change history states “flow fault while sampling point B; work held; instrument inspection requested in a safe location.” If replaced, link the new instrument number and check record; enter valid follow-up measurements in separate rows. Site personnel review all conditions for restart rather than relying only on the sheet.
Failed measurements also have record value. Show which information could not be obtained instead of filling values to eliminate blanks. This illustrates form completion, not an actual accident or company test result.
6. Connect logs, corrections and handovers
Automatic logs help establish instrument-recorded times and values but do not automatically explain sampling locations or ventilation. Align field-record time zones and check instrument clock differences. Use instrument and job numbers or other necessary identifiers in data filenames.
Keep original content, correction reasons, author and time traceable. Overwriting raw logs and retaining only cleaned values makes later event reconstruction difficult. Define retention periods and access rights separately under applicable requirements and company document management.
At shift handover, pass on unmeasured items, held work, faults and current ventilation and isolation, beyond “measurement complete.” Testing whether the next shift can determine current status from the same record helps reveal missing fields. Add verbally communicated information that is absent from the document.
Action checklist
[ ] Equipment identification matches job documents.
[ ] Instrument number connects to sensors and inspection history.
[ ] Every value has a gas name and unit.
[ ] Distinguish measurement time, location, depth and direction.
[ ] Record work, ventilation and changed conditions together.
[ ] Mark unmeasured items, faults and overrange separately from 0.
[ ] Connect actions, follow-up measurements and work-decision owners.
[ ] Retain raw logs, correction history and shift handover information.
Before completing forms, see designing a confined-space measurement plan; for connecting instrument logs, see data logging interpretation and management.
Conclusion
A useful measurement record explains the conditions behind readings, rather than simply containing many numbers. Linking time, location, instrument, tester and work status distinguishes normal readings from information gaps.
These forms are a starting point for site adaptation. Separate measurement results and overall work decisions, retaining unmeasured items and change history so subsequent personnel can review the same evidence.
Sources
US OSHA, Confined Space Pre-Entry Check List / Sample Permits: reference for connecting measurements, personnel and controls.
US OSHA, Procedures for Atmospheric Testing: actual measurement, condition verification and response considerations.
UK HSE, Confined spaces: A brief guide to working safely: preparation beyond measurement. These forms are internal site proposals, not copies of Korean statutory forms.