In-Line Valves
click here for Dimensions
These are supplied with flanges, as seen here or with plain ends, for welding directly into a pipeline. Inlets and outlets of mixed sizes may be specified.
In using this type of valve, careful consideration should be given to the possibility of water-hammer damage to other parts of a reticulation system. It may be necessary to install some form of pressure limiting device, see below.
PRESSURE SURGE PROTECTION
Surges of extreme severity can be generated when a large mass of moving
water is brought to a sudden stop by a valve.
This can happen even though the column of water may have moved only
a short distance, such as occurs at the shutting down of a pump, when flow
is reversed and movement occurs while a flap valve is closing.
The resulting water-hammer impact may be severe enough, depending
on mass and velocity, to severely damage pipes or fittings.
A rough ‘rule of thumb,’ used for many years, suggests that a
momentary pressure surge of this nature might be in the order of ten times
the normal static head of the system.
Simple precautions can be taken to keep pressure surges within acceptable
limits. Relief valves, surge towers and vent pipes, are common examples.
It is strongly recommended that in-line valves be provided with some form
of pressure relief, unless it is definitely known that this is not
warranted in the particular instance.
Relief valves fitted to our in-line n-r valves, for irrigation purposes, are usually 150mm diameter, with a Table D flange. Provision of a matching branch pipe on the valve body needs to be specified when ordering.
OPTIONS available with IN-LINE VALVES.
(indicate when ordering)
1) Drainage Bypass, typically a 50mm steel line with stop cock, to
allow controlled drainage past a closed flap.
2) Branch Pipe for pressure relief valve. This is usually a
150mm diameter pipe, with a Table D flange. Alternate positions for
branch pipes are indicated on the dimension sheet below.
3) Flanges.
Prices do not include flanges or optional fittings,
which are customer specified.
