Shut-off and drain
To shut the STAP completely, use a 5 mm allen key on the spindle
. STAM ,or STAD, can be shut off
using the handwheel. The valves can be drained by using a 5 mm allen key on spindel
on STAP and
on spindle
on STAM ,or STAD.
Accessories
(Figures 3 and 4)
Allen keys
3 mm
52 187-103
For adjusting
∆
p
L
at
5 mm
52 187-105
Shut-off at
, drain at
and
Probes
Pair
52 196-312
at
and
Single
52 196-313
at
,
,
and
Single with valve 52 196-314
at
,
,
and
Fig. 4 Measurement probes
52 196-312 52 196-313
52 196-314
Pair
Single
Single with
valve
→
←
∆
p
L
1
4
3
2
Fig. 1
Return
Inlet
5
Fig.3 Kv
STAM
No. of turns
DN15 DN20 DN25 DN32 DN40 DN50
1
0.36 2.19 3.07
4.45 6.92 9.49
2
1.02 4.13 5.82
9.75 13.4 18.4
3
3.00 5.15 7.51 12.9 18.2 26.2
4
4.01 5.95 8.26 14.6 20.7 32.9
5D
2D
STAM (STAD)
Fig. 2
General
STAP is a self-acting differential pressure controller for use in variable flow systems, both in heating and
cooling. When the available differential pressure is too high for some components (eg control valves,
thermostatic valves), STAP limits the differential pressure,
∆
p
L,
across the circuits, at a suitable value.
STAP can also be used to stabilise the differential pressure across a control valve, maintaining its authority
close to 1 for a good and stable control. STAP is available for the ranges 5-25 kPa and 20-60 kPa with
factory presetting of 10 and 30 kPa respectively.
Features
STAP also provides drain, shut-off and differential pressure measurements facilities. STAP is comple-
mented by STAM (or STAD) which is used for flow measurement and connection of the signal pipe from
STAP. They also provides drain and shut-off functions.
Installation
Install the valves so that the flow is in the direction shown in figure 1. The valves can be mounted in any
orientation but take care about the distances shown in figure 2 for STAM (or STAD). Connect the signal
pipe
between the two valves (the connections are turnable), then open the drain valve spindle
fully.
The plant should be equipped with strainers. (Do not fit the insulation until the system has been commis-
sioned). If it is necessary to remove the valve bonnet when installing STAP, make sure that the o-ring is
undamaged when refitting it.
Pressure-testing the system
The maximum test static pressure is 2 MPa (20 bar).
Commissioning
Radiator valves or other devices must be adjusted to give the design flow for the desired differential pressure
∆
p
L
. Open fully the control valves or thermostatic heads. Deaerate the system and deaerate also the signal
pipe by inserting a CBI measuring probe through the nipple
, leaving it open until only water emerges.
Flow measurement
Measure the flow through the STAM (or STAD) using a CBI, connected betwen
and
. If the pres-
sure drop is too low (which will be indicated by the CBI), close STAM by the whole number of turns that
will allow flow measurement. STAD can be closed to any position. Re-open the valve after measuring to
avoid an unnecessary pressure drop. Note the flow on the label fitted to the valve, eg q=0,2 l/s (
∆
P=10
kPa). If the design flow cannot be achieved, it may be due to blockages in the system. Find and rectify
the fault and measure again. If the circuit requires a
∆
p
L
that differs from the factory setting, follow the
instructions below.
Setting differential pressure,
∆
p
L
STAP is delivered with a factory setting of 10 respectively 30 kPa, which can be adjusted at site in order
to achieve the design flow. Use a 3 mm allen key, inserting it carefully through the whole in the rubber
seal at
. When the key has been fully inserted and engaged with the end of the inner spindle of STAP,
turn it clockwise to increase
∆
p
L
(or anti-clockwise to decrease ). To change the setting of 1 kPa it takes
1,5 turns for the range 5-25 kPa and 0,5 turns for 20-60 kPa.
Example:
Factory setting = 30 kPa
Required differential pressure = 46 kPa
Turn the inner spindle 0,5 x (46-30) = 12 turns clockwise
The actual differential pressure can be checked using a CBI. Measure it between
and
or between
and
. Note that it takes 2-3 minutes from changing the setting until the required value is obtained.
Systems without pre-settable radiator valves
Use a STAD in the supply pipe in the opposite direction to figure 1. In this case, the pressure drop across
the STAD is included in the controlled circuit (
∆
p
L
). Preset the STAD for a pressure drop of 11 kPa for
design flow. Connect a CBI to the valve, measure the flow and adjust
∆
p
L
on STAP as described until the
design flow is achieved (with all thermostatic heads fully open).
4
English
