At a multi-product chemical terminal, solvent loading is segregated by isolating the two things solvents bring to the site, flammable vapor and static charge, from everything else the terminal handles. Where acids, caustics or non-flammable intermediates share the same loading area, the solvent line typically needs its own hazardous-area boundary, pumps and meters dedicated by product family, a vapor collection path that does not mix with other product vents, and a loading permissive that will not release until the truck ground is verified.
The general loading chain of pump, strainer, meter, control valve and loading arm is covered on our truck loading systems page, and static and vapor control at dedicated solvent facilities has its own page on solvent truck loading. This page deals with the segregation decisions that arise when solvents share a site with other chemicals.
Why solvents need separate treatment at a chemical terminal
A chemical terminal portfolio usually combines corrosive, toxic, reactive and flammable products. For many of them, material compatibility and containment drive the design. Solvents add ignition-source control on top of that. If a bay loads an aqueous solution in the morning and a volatile hydrocarbon solvent in the afternoon, its electrical equipment, grounding arrangement and vapor handling all have to be specified for the most demanding product. Because that raises cost across the whole bay, many terminals concentrate solvent loading on a separate bay or a dedicated group of arms.
What to dedicate and what can be shared
There is no single answer. Each piece of infrastructure has its own balance between the risk of sharing and the cost of separating it. The table below lists the items most often weighed in an engineering review.
Infrastructure item | Risk of sharing | Segregation options |
Loading bay and hazardous area | The flammable-vapor zone extends over equipment serving non-flammable products | Locate the solvent bay separately, or classify the whole bay for the solvent case |
Pumps and suction header | Carryover from the previous product, mixing, seal incompatibility | Pumps dedicated by product family; double block and bleed on any shared header |
Meter and meter run | Residue carried into the next product; calibration no longer valid after a product change | Dedicated solvent meter run; if shared, product-specific meter factors and a flushing procedure |
Loading arm and hoses | Elastomers swelling or dissolving in solvent; drips of the previous product | Product-specific arm; hose and seal materials chosen for the solvent family |
Vapor collection line | Incompatible product vapors meeting in a common header | Separate solvent vapor path; treatment method selected per product group |
Nitrogen supply | Backflow of product into the nitrogen network | Check valves, dedicated distribution branch, pressure monitoring |
Drains and spill collection | Solvent ending up in the same sump as corrosive drainage | Collect flammable and corrosive drains separately |
Control system and recipes | Wrong product assigned to the wrong arm | Tie product, arm and truck matching into the loading permissive chain |
Static electricity: solvents do not all behave alike
The word solvent says little about static risk on its own. For electrostatic assessment, liquids are grouped into low, medium and high conductivity classes. Paraffinic and aromatic hydrocarbon solvents fall into the low-conductivity group: charge is generated in piping, pumps and especially fine filters, and can persist in the liquid for a considerable time once it reaches the truck. Alcohols and ketones count as high-conductivity liquids in electrostatic terms, so charge dissipates faster, but they are still flammable and still need grounding.
At a mixed terminal this distinction has practical consequences. For low-conductivity solvents, typical measures include limiting the flow rate at the start of loading, avoiding splash filling until the fill pipe outlet is submerged, providing enough residence time downstream of filters for charge to relax, and not stirring up immiscible phases such as water in the bottom of the compartment. The pump should not start until truck grounding is confirmed, and that permissive belongs in the same interlock chain as the overfill signal. The permissive architecture itself is described on the grounding and overfill prevention page.
Previous cargo and switch loading
Trucks serving chemical terminals often carry different products from one trip to the next. Loading a less volatile solvent into a compartment that previously held a more volatile product can leave an ignitable mixture in the vapor space. Previous-cargo information, a cleaning certificate and, where needed, inerting of the vapor space therefore belong on the pre-loading checklist, along with a chemical compatibility check between the previous cargo and the solvent.
Vapor collection: where does the solvent vapor go?
Vapor displaced from the truck during solvent loading can be captured through closed loading and a vapor collection line. At a mixed terminal, the real question is where that vapor goes. Collecting solvent vapor in the same header as amine, acid or oxidizer vents invites corrosion and unwanted reactions. Vapor return and vapor recovery are different functions; which one applies depends on the product and the emission target, and the solvent vapor recovery page covers the distinction in detail.
Keeping the product clean through changeovers
· Dedicated line: For high-purity solvents, dedicating the tank, pump, meter and arm to a single product removes the cleaning burden altogether.
· Shared line: When solvents of the same family share a line, the changeover sequence, flush volume and quality check on the first load are defined in advance.
· Material compatibility: Ketones and aromatic solvents can swell some elastomers; seal and hose selection is confirmed against manufacturer compatibility data for each solvent.
A short note on meter selection
Magnetic flow meters, common on aqueous products at chemical terminals, need the liquid to exceed a minimum conductivity specified by the manufacturer. Hydrocarbon solvents sit far below that threshold, so conductivity-independent technologies such as Coriolis or positive displacement meters are evaluated for solvent lines. Selection details are on the solvent metering skids and chemical metering skids pages.
How TLY Enerji can support the project
At multi-product terminals, TLY Enerji can provide engineering support for selecting the measurement and control equipment on the solvent line, integrating loading permissives into a PLC-based control system, and installing, testing and commissioning the flow meters. Which of the segregation measures fall within the scope of supply is agreed on the basis of the terminal's existing infrastructure and the project specification.
Information that helps us review your solvent line
· Full list of products loaded at the terminal and where the solvents fit in
· Safety data sheet for each solvent, in particular flash point, vapor pressure and incompatible materials
· Whether a separate bay or arm group is planned for solvents, and current product assignments per bay
· Previous-cargo policy for trucks and how cleaning certificates are handled
· Current status of vapor collection, nitrogen blanketing and vapor treatment
· Purity targets and an acceptable changeover procedure
· Hazardous area classification study and control system interface requirements
Related pages
· Solvent truck loading systems: Static and vapor control at facilities that load solvents only.
· Grounding and overfill prevention systems: How ground verification and overfill signals are wired into the loading permissive.
· Chemical truck loading systems: The broader framework for contamination and emission control in chemical loading.
· Solvent vapor recovery and vapor return systems: Handling collected solvent vapor by balancing, recovery or combustion.
· Solvent metering skids: Choosing meter technology for low-conductivity solvents.
Solvent loading at chemical terminals: FAQ
Can solvents and corrosive chemicals be loaded at the same bay?
It can be done, but the bay's electrical equipment and grounding must be specified for the flammable solvent, drains must be kept separate, and material compatibility has to be confirmed for every product. Arms, hoses and seals that suit both product families are rare. For that reason many terminals give solvents their own bay, or at least a separate arm group, and the final decision takes product volumes, loading frequency and site layout into account.
Should the initial loading rate be limited for every solvent?
Limiting the initial rate is mainly a measure for low-conductivity hydrocarbon solvents. With alcohols and ketones, which are high-conductivity liquids in electrostatic terms, charge relaxes faster, although grounding and avoiding splash filling are still required. The actual rate limit and its duration should come from an electrostatic risk assessment that considers the product, fill pipe size and truck design; this page deliberately gives no generic figure.
Can solvent vapor be tied into the terminal's common vapor header?
Only after the chemical compatibility of every other vapor entering that header has been reviewed. Mixing with vapors from oxidizing or reactive products can cause corrosion or unwanted reactions. If compatibility cannot be demonstrated, solvent vapor gets its own collection path and a treatment method suited to that product group.
Can one meter serve several solvents?
Yes, provided the correct meter factor or density setting is applied for each product, the line is drained or flushed at every changeover, and those steps are recorded. For purity-sensitive products, or where the measurement is the basis for custody transfer, a dedicated meter run is usually the simpler answer.