Collection tank for recovered solvent (the receiver after the still, and keeping static from igniting its head space)
The tank that receives recovered solvent from a recovery still · static-accumulating solvents below 100 pS/m, level floats and gauges that can spark, how the tank is filled, inert head space, bonding and grounding checked at 10 ohms or less
A collection tank after a solvent still holds flammable liquid with a vapour space above it and carries a level gauge. Recovered solvents such as toluene, xylene, hexane and heptane are static accumulators, so the tank's filling arrangement, its level instrument and its bonding decide whether a static spark can form inside it.
Receivers and collection tanks for recovered flammable solvents in solvent recovery systems, with their filling, level measurement, inerting and static control. Storage tanks as a product family are covered on the Storage tank page; corrosive reagent tanks on the Reagent storage tank: bulk tanks for corrosive treatment and process chemicals, rated for the chemical's specific gravity and set in a bund page; the still on the Solvent recovery unit (solvent distillation) page; solvent filters on the Solvent filtration skid for solvent recovery (cartridge and basket filter system) page; drum filling on the Filling head for drum and container filling of chemical liquids page; level instruments on the Level gauge page.
CNFX editorial research · Sources checked October 13, 2026 · 3 sources
Static-accumulating solvents and what sparks inside the tank
In its Barton Solvents case study (Valley Center, Kansas, 2007), the US Chemical Safety Board explains that "A liquid whose conductivity is less than 100 pico siemens per meter (pS/m) is generally considered nonconductive"; the VM&P naphtha involved measured 3 pS/m. Its list of static-accumulating flammable liquids that may form ignitable vapour-air mixtures includes cyclohexane, n-heptane, benzene, toluene, n-hexane, xylene, ethyl benzene and styrene. [1]
The CSB found that stop-start filling, air in the transfer piping and sediment and water in the tank caused rapid charge accumulation, and that the level gauging float had "a loose linkage that likely separated and created a spark during filling". It also notes that the charging rate in pipe flow "increases roughly with the square of the flow velocity"; the transfer ran at 4.6 m/s. [1]
For tanks with conductive loose-linkage floats, the CSB lists inerting the head space, replacing floats with devices that will not promote sparks, bonding the float, reducing pumping velocity, and removing slack in the gauge tape. It warns that inerting can leave the tank oxygen-deficient when opened, and that anti-static additives should be checked with the liquid's manufacturer before relying on them. [1]
List each solvent the tank will receive with its conductivity, and ask the supplier which level instrument, inlet arrangement and inerting they propose for static accumulators.
02
Bonding, grounding and filling from the top
Newson Gale, a maker of static grounding equipment, says the guidance documents it lists "benchmark the total resistance present in the ground loop circuit to an electrical resistance threshold of 10 ohms or less". It explains that while about 1 megohm would dissipate static, a higher reading in an all-metal circuit points to loose or corroded connections. [3]
In a second case study, on a 2007 fire while top-filling a steel tote with ethyl acetate, the CSB lists among its key lessons: "Use bonded and grounded metal dip pipes when top-filling portable tanks". It cites NFPA 77 as saying portable metal tanks and IBCs should be bottom-filled if possible, at 1 m/s or less until the dip pipe is submerged to about 150 mm. [2]
The CSB's naphtha study adds that "bonding and grounding measures applied to typical transfer and storage operations may not be enough if nonconductive flammable liquids are involved". [1]
Ask for the tank's earthing points, the bonding of the inlet pipe, gauge and float, a resistance check at 10 ohms or less, and how the inlet is arranged so the liquid does not free-fall into the vapour space.
03
Recovered solvent collection tank details
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Compiled and source-reviewed by the CNFX editorial team.
Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review
· Page last updated 13 October 2026
Buyer questions
Which solvents accumulate static?
The CSB lists cyclohexane, n-heptane, benzene, toluene, n-hexane, xylene, ethyl benzene and styrene among them. [1]
Can a level float cause an explosion?
In the Barton naphtha tank, a loose float linkage likely separated and sparked during filling. [1]
What grounding resistance should be checked?
Newson Gale benchmarks 10 ohms or less for the ground loop. [3]
Is bonding and grounding enough?
The CSB warns it may not be enough with nonconductive flammable liquids; inerting or slower filling may also be needed. [1]
Sources and what still needs a direct check
Sources checked 2026-10-13. The US Chemical Safety Board publishes its Barton Solvents case studies (2008); Newson Gale publishes a summary of static grounding standards and guidance.
