---
title: How to Specify and Buy a Gas Analyser
url: https://www.sarveshanalytics.com/learn/track-choosing-and-buying.html
description: How to specify an online gas analyser, decide the accuracy you need, compare quotes, count total cost and ask a supplier the right questions.
updated: 2026-11-03
source: html
---

Learn · Track 8 of 8

# Choosing and buying

Specifying, accuracy needs, total cost, comparing quotes and supplier questions.

 6 lessons About 20 min

## What this track covers

The cheapest mistake is the one made on paper. This track turns everything before it into a specification you can send to any supplier, a way to compare what comes back, and the questions that separate a supplier who will support you from one who will only ship you a box.

## Lessons, in order

1. [  **How to specify a gas analyser: A practical checklist** A good specification states the question the number must answer, then the measurement (gas, range, accuracy, response), the sample (composition, pressure, temperature, dust, moisture), the site (area classification, ambient limits, utilities), the outputs and standards, and the support needed.  Intermediate*4 min*](https://www.sarveshanalytics.com/learn/how-to-specify-a-gas-analyser.html)
2. [  **What accuracy do you really need from a gas analyser?** Start from the tolerance the process or product can bear, then build an error budget: sensor accuracy, calibration gas uncertainty, drift between calibrations, sample effects and pressure and temperature effects.  Intermediate*4 min*](https://www.sarveshanalytics.com/learn/what-accuracy-do-you-really-need.html)
3. [  **Total cost of ownership of a gas analyser** The analyser is often a third or less of the cost of a working measurement.  Intermediate*3 min*](https://www.sarveshanalytics.com/learn/total-cost-of-ownership-of-a-gas-analyser.html)
4. [  **How to compare gas analyser quotes like for like** Put quotes side by side on the same scope: what is included in the sample system, what range and accuracy basis (span or reading), what response time and at what flow, certificates and documents, calibration gas and spares, commissioning and support, and what is excluded.  Intermediate*3 min*](https://www.sarveshanalytics.com/learn/comparing-gas-analyser-quotes.html)
5. [  **Questions to ask a gas analyser supplier before you buy** Ask about application experience on streams like yours, what the analyser cannot take, how the sample is handled, what certificates and documents come with it, how calibration works, what spares and service you can count on, and what the supplier does not claim.  Intermediate*3 min*](https://www.sarveshanalytics.com/learn/questions-to-ask-a-gas-analyser-supplier.html)
6. [  **The application data sheet: what to send Sarvesh** The application data sheet collects the pre-order design inputs an engineer needs: the measurement points and gases, ranges, sample pressure, temperature and dew point, dust and corrosives, area classification, utilities, outputs and calibration approach.  Beginner*3 min*](https://www.sarveshanalytics.com/learn/the-application-data-sheet-and-what-to-send-us.html)