Lbs vs. Gals — Which is best?

As a firm that has in excess of 3,000 products/package sizes and a customer base spanning 35 states, we see a wide range of pricing variables in the market.

The old industry standard for pricing chemicals was hundred weight (cwt), or more commonly, price per 100 pounds. We often see price per package and price per gallon, and of course, price per pound. While all have merit, buying chemicals by $/LB is the most reliable. Why? Because all packaged products by reputable suppliers are filled to a specific weight.

At Coyne, all of our pails, deldrums, drums, and totes are filled on scales that are tested prior to every drumming run, utilizing weights certified by an outside agency for accuracy. Due to the vast amount of chemicals we offer, like many other suppliers, it is extremely difficult to adjust package filling procedures due to several variables. Those variables are, Specific Gravity (SG) or weight per volume, temperature, and product volatility.

How do those variables impact accuracy and net weights?

To accurately measure a product by volume (gals), the product’s SG must be known. The SG can be found on the Certificate of Analysis (CofA) provided upon delivery if requested. The product SG x 8.34 will yield an accurate weight per gallon based upon the temperature of the product at the time of filling. However, temperatures are never the same and many products are manufactured to a specification range. Examples are:

 

Product Specific Gravity Range
Ferric Chloride 37-40% 1.38 – 1.49
Sodium Hypochlorite 15% 1.18 – 1.21
Aluminum Sulfate 48-50% 1.32 – 1.34
Caustic Soda 48-50% 1.51 – 1.55

 

So, to allow for product variability, most packages are not filled to a maximum volume (i.e. 15-gallon, 55-gallon, 275-gallon). And, based upon what’s noted above, the volume will vary each and every time depending on the SG. Add into that the product’s ability to “off-gas” and build up internal pressure — those packages are generally filled to a lesser volume to allow for that expansion. Examples are:

 

Product Package Net Weight Approximate Volume
Sodium Hypochlorite 15% 510 lbs 51 gals
Hydrogen Peroxide 50% 500 lbs 50 gals
Aluminum Hydroxide 22% 385 lbs 50.73 gals

 

Therefore, you CANNOT assume that a 55-gallon capacity drum contains 55 gallons. The same can be said for other package volumes.

Knowing the net weight of the package you are purchasing is key, along with accurate and consistent product information. Coyne Chemical Environmental Services remains committed to providing you with quality products at economical costs.

Should you have any questions or concerns about products you purchase, feel free to contact your Chemical Applications Specialist or our offices.

We are always looking for ways to improve at Coyne Environmental Services. Please feel free to submit suggestions through our Contact Us link. Subscribe to our blog for monthly procedural, technical, and informational updates. We’ll even buy you a cup of joe for helping us stay in touch.

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