Sizing & Measuring

Make sure the tank fits your space, know how much it holds, and read its level accurately.

1. Measure your space

Footprint: the tank's diameter (or length and width), plus room for fittings, valves and plumbing, and room for routine work and maintenance.
Height: the overall tank height plus top fittings, the vent and room to make connections. Cone bottom tanks add the height of the stand. Insulated tanks are larger outside: about 4" wider and 2" taller with 2" insulation, 6" and 3" with 3", and 8" and 4" with 4".
The way in: door widths, ceiling heights and turns between the truck and the base. A tank that fits the room may not fit through the door.
Exact dimensions: every tank page has a PDF drawing with its diameter, height and fitting locations.

2. Know your capacity

The listed capacity on each tank page is calculated to the top of the straight sidewall. A tank may be filled "brim" full if it is done with care.

Dense liquids need a tank rated for their specific gravity (SG), not just their volume. Check the SG rating on the tank page.

3. Gallons per inch

For the straight-wall part of a vertical round tank:

Gallons per inch = diameter × diameter × 0.0034

Diameter in inches. Example: a 48" diameter tank holds about 7.8 gallons per inch of depth, so 30 inches of liquid is about 235 gallons. Cone bottoms and domed tops hold less per inch.

Strapping charts. For an exact table of gallons at each inch of depth, open the Strapping Chart button on the tank's page (single wall vertical, double wall and cone bottom tanks). Charts are calculated from each tank's dimensions. Wall thickness varies from tank to tank and HDPE can expand or contract up to 3%, polypropylene about 2%, PVDF moves slightly with temperature, so use a chart as a close guide.

4. Reading the level

We generally offer three ways to read a tank's level (see fittings & options):

Reverse float level indicator

A simple mechanical way to track the fill level. It needs no sidewall penetrations, which makes it especially good for double wall tanks.

Sight gauge

Clear PVC tubing between welded or bulkhead fittings near the top and bottom of the tank, with a ball valve at each end and supporting arms and pipe hangers. Sizes from 1/2" to 3", others available.

Sight glasses can break from impact and cause a spill. Protect them, and never use one on a double wall tank.

Ultrasonic sensor and display

A non-contact Flowline EchoSonic II ultrasonic level transmitter (PVDF transducer for corrosive liquids, 4–20 mA output, ranges from 9.8 ft to 32.8 ft) with a Flowline DataView level controller that shows gallons, liters, inches, feet, meters or percent, and can switch pumps, valves and alarms with optional relays. The sensor ships separately from the tank.

Still have a question?

Call Dan Miller at 936-228-1520 (Mon–Fri, 8 AM–5 PM Central) or send us a message.