Checked against the Marketing Discipline Guidelines 2024 (Ver. 1, effective 24.10.2024) on 15 October 2026. Published by MDG Services on 19 October 2026.
The three samples, side by side
MDG says "3-tier" but never lists the tiers MDG 2.1. This page takes them to be the three samples the lab compares MDG 2.5(G).
| Supply location sample | Tank lorry sample | Nozzle sample (RO sample) | |
|---|---|---|---|
| Drawn by | The supply location, at the filling point where lorries are loaded MDG 2.2.1(i) | The dealer or his representative MDG 2.2.2.1 | An oil company official, mobile lab or other authorised sampler MDG 2.2.2.2 |
| When | Every day, and again after a switch of storage tank MDG 2.2.1(i) MDG 2.2.1(ii) | On every tank lorry, before decanting MDG 2.3 | At random, or after a trigger such as a failed density test or stock variation past the limit MDG 2.4 |
| Size | At least 4 x 1 litre of MS and 2 x 1 litre of HSD MDG 2.2.1(i) | 2 x 1 litre of MS and/or 1 x 1 litre of HSD MDG 2.3 | Per tank, 6 x 1 litre of MS or 3 x 1 litre of HSD, in three equal sets MDG 2.4.1 MDG 2.4.2 |
| Held by | The supply location MDG 2.2.1(iii) | The dealer. The transporter may take a second set MDG 2.3 | The dealer, the oil company's division, territory or regional office, and the lab MDG 2.4.1 MDG 2.4.2 |
| How long kept | At least 30 days MDG 2.9.1 | The two latest loads for each tank MDG 2.9.2 | Until testing and what follows it are finished MDG 2.9.2 MDG 2.9.3 |
The lab tests the nozzle sample against the latest tank lorry sample and the supply location sample that goes with it MDG 2.5(G).
Where to go next
- On every tank lorry, check density and dips first. Then draw, seal, label and sign your sample before you decant, and keep the samples from the two latest loads for each tank MDG 1.2(x) MDG 2.3 MDG 2.9.2. The steps are in the tank lorry retention sample.
- An inspector at your pump: inspector samples and the mobile lab.
- A result that fails: what happens when a sample fails.
Note: if you cannot show your tank lorry samples at an inspection, a sample you produce later is not considered for testing, and any action is against the dealer only MDG 2.5(E).
In this section
Questions dealers ask
01What is 3-tier sampling at a petrol pump?
It is the method MDG 2024 uses to show that the petrol and diesel an outlet sells is what its oil company supplied. The lab compares three samples of the same fuel MDG 2.1 MDG 2.5(G).
02How long does a fuel sample test take?
The preferred times are 10 days for the sample to reach the lab, the next 15 for testing, and 5 days after the report for the result to reach the dealer, about 30 days from drawal in all MDG 2.10 MDG 2.5(F). In special drives the preferred times are 15 days to reach the lab and 30 days from receipt to finish testing MDG 2.10.
03Which standards are fuel samples tested to?
Petrol to IS 2796, IS 17586 and IS 17021, and diesel to IS 1460 and IS 16531, with the tests listed in Annexure 5 MDG 2.10 MDG Annexure 5. Indian Standards are revised from time to time, so check the current version of each.
Read the official text: Marketing Discipline Guidelines 2024 (PDF on Bharat Petroleum's website) (also published on iocl.com).
Related pages
About Dealer Kavach (advertisement)
Dealer Kavach is an app from MDG Services that tracks your outlet's filings, renewals, inspections and daily reports, and reminds you before deadlines, in Hindi and English.