A conventional instrument installation connects the process tapping to the instrument through a run of impulse tubing, assembled on site from tube, fittings, valves and supports. Every one of those joints is a potential leak path, an installation labour hour, and something to be found and fixed at commissioning.
A close-coupled or pre-fabricated hook-up integrates the isolation, equalisation and venting functions into sandwich-construction valve bodies mounted directly at the instrument. The impulse run is either eliminated or reduced to a short, factory-made assembly.
The saving comes from four places. Fewer joints - each joint removed is a leak path removed, permanently. Less site labour - assembly moves from a platform in the weather to a bench under controlled conditions. Faster commissioning - pre-tested assemblies arrive leak-checked, so commissioning finds fewer faults. And less mass and vibration - a shorter run has fewer resonance problems and needs less support.
The case is strongest where site labour is expensive or access is difficult, where the medium makes a leak consequential, and where a plant is repeating the same instrument installation many times - in which case a designed and validated hook-up can be replicated exactly rather than assembled slightly differently by each fitter.
We design hook-ups to the specific application: process conditions, instrument type, mounting arrangement and the standards the installation must meet. Assemblies are built and tested before dispatch and arrive ready to install.