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Gas cylinders: a 20-pound tank must contain 20 pounds

Last reviewed: August 23, 2026VerifiedDACO

In short

An estimated 600,000-plus households in Puerto Rico use gas appliances, and for years the market had a problem that is simple to name: tanks with a twenty (20) pound capacity were sold whose real weight varied between fifteen (15) and seventeen (17), and the consumer had no way to check. Act 18-2022 solves it by definition. Every gas company that fills cylinders must use the services of an Authorized Public Weigher (PPA) to determine the tare and net weight of its product, and may only distribute and sell in cylinders with capacities of twenty (20), fifty (50), one hundred (100) pounds and others, taking into account that each cylinder with a twenty-pound capacity shall contain a net weight of twenty pounds of gas, the fifty shall contain fifty and the one hundred shall contain one hundred, with the tolerances or permissible variations set by law or regulation. For cylinders of other capacities, the net weight shall be as the manufacturer provides. And every gas company that fills cylinders must label them clearly indicating their net content. Two agencies watch: DACO, which polices seal calibration under the Weights and Measures Act, and the Transportation and Other Public Services Bureau, which regulates the market and grants the franchises.

External link

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What is it?

The law works with three pieces worth telling apart. The tare is the weight of the empty cylinder. The net weight is the weight of the gas the cylinder contains, excluding the tare — it is what you buy. And the seal is the stamp, tie or band that keeps a valve closed so it cannot be opened without breaking it; sealing means placing it on every outlet valve, except overflow valves, in order to certify the net weight of the filled gas and the cylinder’s tare. The one who certifies is the Authorized Public Weigher, a natural person authorized by DACO’s Secretary to certify the correctness of measures under the Weights and Measures Act, and their certification stays on the tag: the moisture-proof label or sticker, posing no fire hazard, attached or tied to the cylinder with resistant material such as metal or plastic.

Who can do it?

The law defines "consumer" as the person who buys one or more gas cylinders for use and consumption at their home, or to use in their business, fixed or itinerant, in preparing food for sale to the public, or for any other use. The duties fall on the "gas company", understood as anyone who supervises, controls, operates, manages or owns any activity of filling, storing, transporting, delivering, wholesaling or retailing, supplying or distributing gas packaged in cylinders, and it includes anyone who in any way takes part in those activities.

Requirements

Information pending verification.

Documents you need

Information pending verification.

Cost

The cost depends on your situation. Check which cost applies with the official agency.

Step by step

  1. Step 1: Look at the capacity and expect that net weight

    Twenty pounds of capacity, twenty pounds of net gas weight. Fifty, fifty. One hundred, one hundred. All with the tolerances or permissible variations set by law or regulation. For cylinders of other capacities, the law says they shall contain the net weight in pounds of gas as the manufacturer provides. Before this law, the retailers’ own complaint was that tanks with a twenty-pound capacity were sold filled with fifteen or seventeen, and the consumer had no adequate mechanism to determine or check the real capacity to which the cylinder had been filled.

  2. Step 2: Look for the net content label

    Article 4 closes with a short duty: every gas company engaged in filling cylinders shall label the cylinders clearly indicating their net content. It is the first thing to look at on the exchange rack, and if the cylinder does not say it, that is the question to ask before paying.

  3. Step 3: Check the seal and the tag

    The seal keeps the valve closed so it cannot be opened without breaking it, and its function is to certify the net weight of the filled gas and the cylinder’s tare. The tag is where the Authorized Public Weigher certifies the cylinder: a moisture-proof label posing no fire hazard, attached or tied with resistant material. A cylinder with no seal or no tag is not complying with what the law describes.

  4. Step 4: Compare price to quantity, not to the tank

    The law’s statement of motives records the fact that explains why this matters: at a public hearing, DACO reported that consumers in Puerto Rico were paying more for a cylinder with fifteen pounds of gas than for one containing seventeen or twenty. The same section mentions DACO’s 2016 order requiring wholesalers and retailers to post on exchange racks, or any other place designated for sale, the cylinder’s price and its net content, including both the exchanged cylinder price and the non-exchange price.

  5. Step 5: If the weight does not add up, file with DACO

    DACO polices seal calibration so consumers can verify that the amount of gas they are buying is the amount they are told, and it does so under the Weights and Measures Act. Services and regional offices are at daco.pr.gov and online filing at serviciosenlinea.daco.pr.gov. If the complaint is about the company’s franchise or about filling, selling, repairing or rebuilding cylinders, that jurisdiction belongs to the Transportation and Other Public Services Bureau.

Where to do it

Two agencies, each in its lane. The Department of Consumer Affairs polices seal calibration under Act 145-1968 on Weights and Measures and authorizes the Authorized Public Weighers. The Transportation and Other Public Services Bureau of Puerto Rico regulates the liquefied gas market under the Public Service Act, including granting franchises to gas companies and to cylinder filling, sale, repair and rebuilding companies, gas pipelines and oil pipelines, with power to regulate, authorize, oversee, inspect and impose administrative fines.

How long it takes

Check the current processing time with the official agency.

What to do if something goes wrong

Three things this guide deliberately leaves open. First, the tolerances: the law says "with the tolerances or permissible variations set by law or regulation" and refers, for other tags and presentations, to Handbook 133 of the National Institute of Standards and Technology, its supplements and revisions. We did not read Handbook 133, so we cannot tell you how many ounces of difference are lawful. Second, the price: DACO publishes average gas prices, but this law sets no prices or caps, and the statement of motives itself notes the Department published averages only for twenty and one hundred pounds. Third, the fine: this law establishes no penalty of its own; enforcement runs through the Weights and Measures Act for DACO and through the Public Service Act for the Bureau, which can impose administrative fines. A note on filling, in case anyone tells you filling to capacity is dangerous: the law refers cylinder filling to 49 CFR 173.315(n), to pamphlet number 58 of the National Fire Protection Association, and to the Bureau’s applicable regulation. That argument did happen — it is recounted in the statement of motives, with litigation involved — and the Legislature settled it by writing the rule into the statute.

Common mistakes

  • Comparing prices between tanks without looking at the labeled net content.
  • Assuming a "20-pound" cylinder holds 20 pounds just because the tank says so: what certifies the weight is the PPA’s seal and tag.
  • Paying without seeing the net content label, which the law requires of every filling company.
  • Taking a weight complaint to the Bureau and a franchise complaint to DACO: each agency has its own jurisdiction.
  • Looking in this law for how many ounces of tolerance are lawful; it refers to NIST Handbook 133.
  • Expecting a fine set by this law: enforcement runs through Weights and Measures and the Public Service Act.

Frequently asked questions

How much gas should a 20-pound cylinder contain?

Twenty pounds of net gas weight, with the tolerances or permissible variations set by law or regulation. Net weight is the weight of the gas excluding the tare, which is the weight of the empty cylinder.

Who certifies the tank is properly filled?

An Authorized Public Weigher (PPA): a natural person authorized by DACO’s Secretary to certify the correctness of measures under the Weights and Measures Act. Every gas company that fills cylinders must use their services to determine the product’s tare and net weight.

Can they sell me a tank without saying how much it holds?

The law requires every gas company engaged in filling cylinders to label them clearly indicating their net content. In addition, per the statement of motives, a 2016 DACO order required posting on exchange racks the cylinder’s price and its net content, both exchanged and non-exchange.

Who do I complain to if the tank comes short?

The Department of Consumer Affairs, which polices seal calibration under the Weights and Measures Act precisely so the consumer can verify the amount they buy is the amount stated. If the matter is about franchising or about cylinder filling, sale, repair or rebuilding companies, jurisdiction belongs to the Transportation and Other Public Services Bureau.

Official sources

These are the government pages this guide is based on.

Last verified

August 23, 2026

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