© TT Electronics plc

Issue B 7/2017

Page 3

TT Electronics | Roxspur Measurement & Control Ltd

2 Downgate Drive, Sheffield, S4 8BT, England |Ph: +44(0)114 244 2521

www.roxspur.com | sales@roxspur.com

General Note

TT Electronics reserves the right to make changes in product specification without

notice or liability. All information is subject to TT Electronics’ own data and is

considered accurate at time of going to print.

Platon Gapmeter Type SGUV &

SGUL

DS1160

The By-Pass Piping connecting the Main Orifice and Gapmeter is normally rigid (SGUV version) so that the whole assembly is han-

dled as one unit.For most applications copper pipe and brass compression couplings are used, but these parts can be all of 316

Stainless Steel or rigid PVC where necessary. It is vital that the pressure loss due to friction in the by-pass pipe is constant as any

change affects the calibration of the assembly. Where the SGUV assemblies cannot be used, flexible nylon pipe (SGUL version) can

be supplied for a maximum “reach” of 25 feet.

CALIBRATION

The Main Orifice is calculated from data supplied by the user to provide a pressure-differential range to suit a standard Gapmeter

assembly, all other components are dimensionally interchangeable. Calculations are made on the assumption that BS EN ISO prac-

tice is followed for the main orifice installation, e.g. straight pipe requirement for maximum capacities are 20 diameters upstream

and 5 downstream.

The Gapmeter tube is scaled as close as possible to the user's needs as the criterion of interchangeability allows. All figures and lines

are printed to a high reading standard. Arbitrary scales and charts are available where one indicator may be used with several main

orifices, or under varying conditions of pressure or temperature. With proper installation, accuracy of ±2.5% of full-scale reading is

achieved.

INSTALLATION

The best place for a Shunt Gapmeter is in a straight length of horizontal or vertical pipe at a flanged joint easily accessible for read-

ing purposes; the flow may be in any direction. If such a position does not exist, a straight pipe should be selected and long reach

fittings used so that the Gapmeter indicator can be mounted conveniently for reading on a wall or panel.

The orifice carrier must be centred within the pipe flanges so that the orifice is co-axial with the pipe and so that the approach bore

is smooth. The direction arrow must be aligned with the flow. Gaskets must not project into the pipe bore for the same reason: they

are best cut with the inside diameter 10% oversize. The approach pipe must be of smooth bore and non-corroding.

The relative positions of the Main Orifice and Gapmeter are best determined by the need to avoid condensation in the indicator

when measuring gas flows, and the need to obviate air locks when measuring liquids. Wherever possible ensure that with liquids the

Gapmeter is below the orifice and with gases that the Gapmeter is above the orifice.

Close coupled vertical orientation for gaseous flows.

Close coupled horizontal orientation for liquid flows.

ORDERING DETAILS

Nature of fluid (and details of density and viscosity, if unusual). State any corrosion hazard. Working conditions of temperature and

pressure.

Whether pressure test certificate required.

Details of size, orientation of pipe and existing flange drilling.

Direction of flow and whether close-coupled or long-reach fittings are required.