Metso NE727 User Manual

7 NE 72 en 13
9.2 Mechanical defects
1. A change in the input signal does not affect the position
of the actuator.
 supply pressure too low
 diaphragms damaged
 pilot valve sticks
 seals in the changeover piece leak
 tubes between the positioner and the actuator,
change-over piece or position of the cam wrong, see
Fig. 6
 actuator and/or valve jammed
 restriction assembly blocked, see Fig. 17
2. The actuator goes to the final position with a small
change input signal.
 tubes between the positioner and the actuator, the
changeover piece or the position of the cam wrong.
3. Inaccurate positioning
 pilot valve dirty
 beam (5) pushes the pilot valve spool sideways
 diaphragms damaged
 dirt in the magnet air gap
 actuator torque too low
 supply pressure too low
 valve torque requirement increased
4. Overshooting or too slow
 positioning setting for the internal feed-back spring
wrong
 pilot valve dirty or of the wrong size, see Table 2
 supply air tube too small or supply air filter dirty
 valve sticks
5. Zero point unstable
 restriction assembly dirty
 inaccurate dead angle α
0
adjustment
10 OPTIONS
10.1 NE700/R dust-proof construction (IP65)
For extremely dusty environments. The protective cover (3)
behind the standard posioner is replaced with an exhaust
port with a 3/4 NPT filter.
Please note: do not remove the exhaust port.
10.2 NE700/A with pressure gauges
The positioner (manufactured after 9/92) can be equipped
with a pressure gauge block. The block (70) is attached with
tree sef-tapping screws (72). The O-rings (71, 3 pcs.) must
be in position before mounting. Check tightness after
mounting.
For all other constructions see Type code, Chapter 14.
11 TOOLS
In addition to standard general tools, you need the follow-
ing equipment:
 calibration device for adjustments
 multimeter
12 ORDERING SPARE PARTS
When ordering spare parts, always include the following
information:
 type code, sales order number, serial number
 number of the parts list, part number, name of the
part and quantity required
This information can be found from the identification plate
or documents.

Metso NE727 Specifications

General

Brand	Metso
Model	NE727
Category	Valve Positioners
Language	English