GAS PURIFICATION · BUYER’S DATA CHECK
Gas Analysis for Adsorbent RFQs: Units, Dry/Wet Basis and Sample Location
A concentration without its reporting basis can lead to two suppliers quoting for different duties. Send a complete gas-analysis record before comparing media recommendations.
Three checks before comparing the numbers
What was measured?
Keep the named compound, result and unit together. Ask whether a grouped result is reported as total compounds, carbon equivalent or a named reference substance.
What does the unit mean?
Specify volume or mass basis, reference temperature and pressure, and whether the result is dry or wet. Preserve any correction stated by the laboratory.
Where was it sampled?
Identify the actual adsorber inlet, not just the process name. Mark any cooler, separator, dryer or filter between the sample point and the bed.
Do not treat ppmv and mg/m³ as interchangeable
PPMv describes a volume ratio; mg/m³ describes mass per gas volume. Converting between them requires the substance’s molecular weight and the relevant temperature and pressure. EPA’s gas-unit guidance specifically warns against treating gas-phase mg/L as equivalent to ppmv.
Likewise, keep the moisture basis attached to the result. A dry-basis value and a wet-basis value are not directly comparable without the information needed for a valid conversion. If an emissions report includes an oxygen-reference correction, ask the process engineer or laboratory for the appropriate inlet-process basis before using it in media selection.
A quote-ready gas-analysis pack
The following purchasing record helps the supplier state exactly which duty the offer covers.
- Stream and equipment: process name, vessel tag, operating mode and sample-point sketch.
- Analysis: named components, units, test method, sampling date and report reference. Keep qualifiers such as “less than” with the reported value.
- Reporting conditions: actual or reference temperature and pressure, dry/wet basis, and any normalization or correction.
- Operating envelope: normal and expected peak conditions, operating hours and known feed changes. Identify which figures are measured and which are design requirements.
- Flow basis: flow at the bed and its reference conditions. Concentration and flow must be put on compatible bases before deriving a mass loading.
- Outlet requirement: target component, unit, sampling point, averaging period and the evidence needed for acceptance.
- Existing installation: current media grade, bed dimensions, refill quantity and relevant pretreatment. Include prior operating observations if available.
Turn incomplete reports into useful clarification requests
A result says only “ppm”
Ask the issuer to identify whether it is a volume or mass basis. Do not fill in “ppmv” on their behalf.
A result is below a reporting limit
Preserve the qualifier and reporting limit. Ask the technical reviewer how this evidence should be used in the duty specification instead of replacing it with zero.
The sample is upstream of treatment
Label it clearly and ask for representative inlet data or a documented basis for the downstream duty. Do not present an upstream measurement as a bed-inlet test.
What to ask each supplier to return
Request the proposed media grade and form, the feed conditions used in the recommendation, the relevant application evidence, and the operating limits or missing data that affect the offer. Keep media price comparison separate from confirmation that the selected material suits the stream.
Please base your recommendation on the attached gas-analysis report and inlet-condition schedule. State the concentration, moisture and flow bases used, identify any conversions or assumptions, and list the additional information needed to confirm the proposed grade and refill quantity.
This guide organizes quotation inputs; it does not establish bed size, service life or safe operating limits. Those decisions require application-specific engineering review.
Common purchasing questions
Can I compare two reports with the same unit?
First check that the substance, sample point, reporting conditions and measurement scope also match. Matching unit labels alone do not establish comparable duties.
Does a laboratory report prove the adsorbent will work?
No. It describes the sampled stream within the report’s scope. Media suitability and performance still need evidence relevant to the actual application.
Should I send only a summary spreadsheet?
Send the original report as well. A summary helps purchasing, but footnotes, qualifiers and method details can be lost during transcription.
Continue your procurement review
Prepare a comparable adsorbent quotation
Share your application, gas-analysis report, inlet conditions, required outlet quality and quantity. A clear duty basis makes the next technical discussion more productive.
Send your requirementsTechnical references
US EPA: gas concentration unit conversion; UK Environment Agency: concentration and flow reporting bases. These sources explain general measurement principles. The RFQ workflow and clarification examples above apply those principles to industrial adsorbent procurement.