Capacity+ Low Profile Secondary Seal
Optimised secondary sealing for applications with limited vertical clearance
Secondary sealing solution engineered to maximise usable tank capacity while
maintaining effective vapour control and reliable performance across a range of
operating conditions.
Overview
The Capacity+ Low Profile Secondary Seal is a
high-performance secondary sealing solution designed
for floating roof tanks where vertical clearance is limited
and optimisation of usable working capacity is critical.
By combining a low vertical profile with a wide horizontal
working range, the Capacity+ enables operators to
optimise usable tank volume without compromising
sealing integrity. Installed between the floating roof and
the tank shell, the seal works in conjunction with the
primary seal to further reduce vapour emissions and
support regulatory compliance.
Manufactured using robust, spring-steel mechanical
components and a PTFE-wrapped wiper tip, the
Capacity+ is engineered to perform reliably across
variable rim gaps, challenging tank shell conditions, and
demanding operating environments.
Design Highlights
Low vertical profile to optimise usable product capacity
Wide horizontal working range to accommodate variable rim gaps
PTFE-wrapped wiper tip for enhanced abrasion resistance and chemical compatibility
Spring-steel mechanical components engineered for long service life
Suitable for installation in-service or out-of-service
Compatible with a range of vapour barrier fabric options
Wide horizontal working range to accommodate variable rim gaps
PTFE-wrapped wiper tip for enhanced abrasion resistance and chemical compatibility
Spring-steel mechanical components engineered for long service life
Suitable for installation in-service or out-of-service
Compatible with a range of vapour barrier fabric options
Key Benefits

Maximises tank
working capacity
The low-profile design allows operators to recover usable storage volume that may be constrained by higher-profile secondary seals.

Reliable sealing across variable rim gaps
Engineered to maintain consistent contact with the tank shell across rim space variability and shell irregularities.

Reduced vapour emissions
Provides an additional sealing layer that limits vapour escape and supports environmental performance objectives.

Durable, low-maintenance construction
Robust materials and spring-backed components deliver dependable, low-maintenance operation.

Flexible in-service and
out-of-service installation
Designed for safe and efficient installation during both in-service and out-of-service conditions.
Compliance and Standards
The Capacity+ Low Profile Secondary Seal is suited to floating roof tanks where vertical
clearance constraints and performance demands intersect, including:
- Petrochemical storage
- Fuel and hydrocarbon tanks
- Industrial storage applications
- Tanks requiring optimisation of usable working capacity
Compliance & Quality
Capacity+ secondary seals are manufactured under DirecTank’s quality management
system and developed in line with recognised industry standards and regulatory
requirements.
Materials are fully traceable, and designs support compliance with applicable air quality and
emissions control regulations, including classification as a Category “A” secondary seal
where required.