FEATURES
41
Hearts and controls
Before you embark on installing or replacing valves,
pumps, and pipes, it is essential that you are aware of
the South African National Standards (SANS) that apply,
either as mandatory or voluntary standards. We will
cover valves in this issue and pumps in June.
By Rory Macnamara
The pump can be described as the heart, while
the valve controls and the pipe are the aorta. Also,
all pipes, valves, and certain pumps that come
into contact with potable water are mandatory,
so there is no option. Use of a non-compliant
product will lead one into big trouble, whether
specified and installed — never mind the
potential for water losses.
We list the standard number and brief description
thereof as per the SABS website (accessed on 6 April
2017), but the onus is on you to check the status of
the standard, as technical committees meet regularly
and may well be recommending amendments to the
standard. This is signified by the SANS number, year,
and edition, for example SANS 10254:2008 – 5. So,
if you are sitting with the first edition, you need to
update or you will be out-of-date. As both valves and
pumps are part of a system, it would also be wise
to search the SABS website and check. We list the
obvious ones. However, any engineer and installer
worth his or her salt would know about changes.
Because of the functional nature of a valve and a
pump, it is highly likely that another standard may call
up the use of a valve/pump within the context of that
application.
Valves
• SANS 191 – cast steel
• SANS 198 – control and safety
• SANS 664 – cast iron gate
• SANS 665 – wedge gate
• SANS 752 – float
• SANS 776 – copper alloy gate (heavy duty)
• SANS 1006 – plastic ball
• SANS 1056 – ball (fire and non-fire safe)
• SANS 1299 – tempering
www.plumbingafrica.co.za
•
•
•
•
SANS 1509 – flush
SANS 1532 – vent
SANS 1551 1&2 - check
SANS 1808,09,10,13,15,18,31, 32, 35 - family
of standards for water and distribution system
components
Valve descriptions
• Gate valve
The distinct feature of a gate valve is the sealing of surfaces
where the gate and seats are planar, so gate valves are
often used when a straight-line flow of fluid and minimum
restriction is desired. Typical gate valves are designed to be
fully opened or closed.
Gate valves most commonly come in two varieties. The
parallel gate valve uses a flat disc to shut off and control
the fluid flow. It creates a seal to prevent leakage. Parallel
gate valves also have two types: knife valves and through-
conduits. The knife valve has a sharp bottom to cut through
any solids passing through the pipe. The through-conduit
is rectangle shaped with a circular opening to allow fluid to
flow when it is lowered.
So, if you are sitting with
the first edition, you need
to update or you will be
out-of-date. As both valves
and pumps are part of a
system, it would also be
wise to search the SABS
website and check.
Continued on page 42 >>
May 2017 Volume 23 I Number 3