VISATRON VN87plus brochure, Überblick




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OIL MIST DETECTORS

A component of the DIEMOS-System

VN116/87plus

Type
VN115/87plus

87plus

VN215/87plus

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OIL MIST DETECTORS

Brief description

The VN87plus series is distinguished from the VN87 series through the following features:

Function description

Design

All  VISATRON

®

-  devices  continuously  draw  the  atmosphere

from every compartment of the crankcase  through the suction
system.  The suction vacuum required is generated through a
wear- free air jet pump in the device, fed with compressed air
(drive air), and is consequently independent of e.g. an alterna-
ting power supply.
The sample fl ow, consisting of the sucked-in atmosphere of the
crankcase compartment, is guided through an optical channel
for  measuring  turbidity.    The  turbidity  of  the  sample  fl ow  is
measured by the absorption of infrared light.
%  Opacity  is  used  as  the  dimensional  unit  of  the  turbidity;
100% Opacity means total absorption, and 0% Opacity

Oil mist detectors protect large diesel, gas and dual
fuel engines of all applications from heavy conse-
quential damage as a result of overheating of bea-
rings or other moving parts.

means  no  absorption.    Oil  mist  becomes  explosive  from  a
concentration of approx. 47 mg of atomised oil in 1 litre of air
and up, which corresponds to an absolute opacity of approx.
40%.
The  sensitivity,  i.e.  the  opacity  that  is  required  to  trigger  an
alarm, can be set at 4 different levels in all devices.
A slow increase in the operating opacity or the contamination
of  the  optics  is  compensated  in  the  microprocessor  system
up to a maximum safety alarm threshold. The contamination
is strongly limited through scavenging air chambers that are
supplied with fresh air and are located in front of the optics.

With  the  VISATRON

®

oil  mist  detectors  of  the  type  VN

115/87plus  and  116/87plus,  a  header  pipe  sampling  system
is  used  for  suction  extraction  of  the  crankcase  atmosphere
from  each  crankcase  compartment;  whereas  an  individual
compartment  suction  pipe  system  is  engaged  for  the  type
VN215/87plus.

A pre-alarm relay, activated at 70% opacity of main alarm

level, can be activated before an engine stop will be trig
gered based on a high concentration of oil mist (endange
ring the engine).

Scavenging air chambers are not supplied with air from the

engine room, but instead with fresh pressurized air, so fu-
mes from a fi re in the machine room cannot lead to an
alarm and fi lters stay clean for a longer period.

The measuring head heating unit for the avoidance of

precipitating condensation water in the device, which can
be delivered as an option to the VN87, is integrated in the
measuring head of the VN87plus.

An optional RS 485 interface permits the connection of the

VN87plus series to a remote monitoring unit.

The  air  jet  pump,  the  connector  plug,  the  pipe  connector
box  (VN115/87plus)  or  the  valve  box  (VN116/87plus  and
VN 215/87plus) and the shock-absorbing mounting plate for
the  actual  measuring  head  are  supported  on  a  sturdy  base
plate. The opacity measurement path and the electronics with
microprocessor control are located in the measuring head.

1 LED chain and 3 further LEDs to display the operating sta-
te.The measuring heads are designed to be interchangeable
with the ones of VN/87 series.

Page 2

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OIL MIST DETECTORS

Application of the different VISATRON

®

devices and suction systems

Basic design, suitable for the monitoring of trunk piston diesel engines with in-line and V cylinder arrangements, running at

medium and high speed.

In the case of oil mist generation, damage detection through a header pipe sampling system without localisation of the point of

damage.

VN115/87plus

The detection of damage takes place through a header pipe
sampling system without localisation of the point of damage.
The mixture of atmosphere from the crankcase passes from
all  individual  compartments  via  the  header  pipe  through  the

Dimensional diagram

detector‘s pipe connector box into the opacity measurement
path in the housing of the measuring head. The alarm thres-
hold can be set to 4 levels.

Page 3

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OIL MIST DETECTORS

Application of the different VISATRON

®

devices and suction systems

Design suitable for the monitoring of trunk piston diesel engines with in-line and V cylinder arrangements, running at medium

and high speed.

Damage detection through a header pipe sampling system with a display of the crankcase compartment half (left or right side

of the position of the detector) in which overheating damage has arisen.

The header pipe sampling system is the same as in the VN115, so the VN116 can replace the VN115 without modifi cation of

the suction system if localisation of damage is called for.

VN116/87plus

The detection of damage takes place through a header pipe
sampling system with a display of the crankcase compartment
half in which the overheating damage has arisen. The mixture
of atmosphere from the crankcase passes from all individual
compartments via the header pipe through the valve box into
the opacity measurement path in the housing of the measu-
ring  head.  If  the  opacity  of  the  mixture  of  atmosphere  from
the crankcase exceeds 10% of the alarm threshold that has
been set, a so-called damage check starts.  The valves in the

Dimensional diagram

valve box are switched over according to a certain algorithm
during the damage check, until the half of the crankcase com-
partments with the overheating damage has been found. The
alarm threshold can be set to 4 levels. The increased sensitivi-
ty, in comparison with the VN115/87plus, results from the fact
that an alarm is triggered if the difference in opacity between
the two halves of the crankcase compartment exceeds 20% of
the alarm threshold that has been set.

Page 4

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OIL MIST DETECTORS

Device suitable for the monitoring of crosshead engines running at medium and slow speed, ecause the oil mist spreads out

from the damaged compartment more slowly than in the case of trunk piston engines.

Damage detection through the individual compartment suction pipe system, with display of the compartment with the overhea-

ting damage.

VN215/87plus

Dimensional diagram

Application of the different VISATRON

®

devices and suction systems

The detection of damage takes place through a header pipe
sampling system with a display of the crankcase compartment
half in which the overheating damage has arisen. The mixture
of atmosphere from the crankcase passes from all individual
compartments via the header pipe through the valve box into
the opacity measurement path in the housing of the measu-
ring  head.  If  the  opacity  of  the  mixture  of  atmosphere  from
the crankcase exceeds 10% of the alarm threshold that has
been set, a so-called damage check starts.  The valves in the

valve box are switched over according to a certain algorithm during
the damage check, until the half of the crankcase compartments with
the  overheating  damage  has  been  found.  The  alarm  threshold  can
be  set  to  4  levels. The  increased  sensitivity,  in  comparison  with  the
VN115/87plus, results from the fact that an alarm is triggered if the
difference in opacity between the two halves of the crankcase com-
partment exceeds 20% of the alarm threshold that has been set.

Page 5

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OIL MIST DETECTORS

Suction System

VN115/87plus and VN116/87plus:
2 header pipes (22 x 2 mm) with thinner branch pipes (10 x 2 mm) to the crankcase compartments, max. lenght 9m.

VN215/87plus:
Individual pipes (14 x 2 mm) from each compartment to the OMD, max. lenght 9m.

The maximum number of sampling points for both systems (header pipe and individual) =10
Suction pressure measured against atmospheric pressure 60 mmWC. The measurement is performed with a U-pipe manometer on the measuring
head. The U-pipe manometer is a component available in the service box (see accessories).

VN115/87plus:
Alarm threshold 2% Opacity* (see Brief Description of the VN 115/87plus), adjustable in 4 levels from 0,5% to 25% Opacity. (1% Opacity corresponds to
approx. 0,2 mg of oil mist per litre of crankcase atmosphere; explosion limit 47 mg/l at ignition temperature of 270°C).

VN116/87plus und VN215/87plus:
Damage Check - start threshold 0,24% Opacity* (see Brief Description of the VN 116/87plus), adjustable in 4 levels from 0,16% to 0,55% Opacity. Diffe-
rential alarm threshold 0,49% Opacity* (see Brief Description of the VN 116/87plus), adjustable in 4 levels from 0,33% to 1,1% Opacity.  Safety alarm
threshold 2,44% Opacity* (see Column 5, Brief Description of the VN 115/87plus), adjustable in 4 levels from 1,6% to 5,5% Opacity.
*Factory setting

Electric Power Supply
Voltage: 24 V DC - 25/+ 30%, 24 V battery or power supply unit
Note: In case of battery operation, provide a direct power supply from the battery terminals directly to the VISATRON-device!
Current consumption: max. 2 A.

Drive Air for the suction system
Suction vacuum measured against the atmosphere 60 mmWC. The measurement is performed with a U- pipe manometer on the measuring head. The
U- pipe manometer is a component of the service box (see accessories).Air pressure required at the inlet of the jet pump approx. 0,6 bar. Air consumpti-
on max. 1,0 Nm

3

/h (m

3

at atmospheric pressure). The drive air can be taken from the pneumatic engine control system or from the starting air system.

A pressure regulation unit (see device list) can be delivered as an option for pressure reduction; max. inlet air pressure 15 bar (additional 30 bar pressure
regulator is also available).

Sensitivity

Power Supply

Signal Outputs and Displays

Technical Data

Main Alarm
Adjustment range for the sensitivity: can be set to 4 levels
Remote Signalling: relay with 2 potential-free switch-over contacts,
excitation with a main alarm.
Contact load max. 60V DC, 1 A, 60 W
Wire-Break Protection: bridging  the n.o. contacts with 33 K ohm resis-
tor. On request, resistor with other value is available.
Display on the device: permanently on red Alarm Led

Pre-Alarm
Factory Pre-Set to 70% of the main alarm threshold, not changeable.
Remote Signalling: relay with potential- free contact, opens for a pre-
alarm.
Contact load max. 60V AC, 2 A , 120 VA / max. 60 V DC, 2A, 60W

Fail-Safe Alarm, Indication of Device in operation
Remote Signalling: Relay with potential-free switch-over contact, excita-
tion when the device is functioning troublefree. Contact load max. 60V
AC, 2 A, 120 VA/max. 60V DC, 2 A, 60W
Display on the device: green Ready-LED on when the device is functio-
ning troublefree

Opacity Display
Remote Signalling: By a remote indicator, driven through the optional
RS 485 interface
Display on the device: By LED chain with 14 LED‘s display of the
opacity relative to the alarm threshold in 14 steps, i.e. the main alarm is
triggered when the upper LED is reached.

Cable Connections
M25 x 1,5 screwed connections for the cable connection of the relay
contacts
M25 x 1,5 screwed connections for the cable connection of the power
supply

Mechanical Data / Temperature
Housing and base plate: cast aluminium. Support plate for the measu-
ring head: stainless steel plate with anti vibration suspension.
All surfaces: lacquered, RAL 7035. Springs, bolts etc.: stainless stell.
Rubber parts for vibration reduction and selas: oil resistant. Built-in
vibration
reduction for the electronic part. System of Protection IP 54. Operting
range:
0°C to 70!C. Storage temperature: -25°C to +80°C

VN 115/87plus net weight: 7,5 kg,
Gross with special packing: 12,5 kg
VN 116/87plus and VN 215/87plus net weight: 9,4 kg,
Gross with special packing: 13,5 kg

Page 6

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OIL MIST DETECTORS

VISATRON

®

assembly system

VISATRON

®

assembly system

Comprehensive  investigations  on  different  types  of  engines
have made clear that the sampling points for the oil mist have
to be placed in the interior of the crankcase at points where
the highest possible concentration of oil mist can be extrac-
ted, in case of damage, without a loss of time. The concentra-
tion of the drawn oil mist is the message as to the condition of
the crankdrive for the oil mist detector. It becomes imperative
that a genuine information is trans-mitted as a signal with the
greatest possible intensity from the point of oil mist genera-
tion, so that the sensitivity of the oil mist detector doesn‘t have
to be set unnecessarily high. Otherwise, interfering infl uences
are also received and evaluated.
One of the most important requirements for a well-functioning
oil mist monitoring system is the absolute necessity of avoi-
ding false alarms. In addition, the way the suction system is
installed  on  the  engine  is  of  great  importance.  Precipitated
oil can accumulate in the piping system, therefore provisions
have to be made to drain it back into the crankcase, to avoid
that the suction pipes become clogged. If the pipes are fi tted
conventionally, they must  be installed with a slope ensuring
the drainage of oil at all times.

Illustration  1

shows  the  conventional  installation  of  a

VISATRON

®

oil mist detector. The pipes have the necessary

slope for the return of the oil that

has precipitated from the oil mist. Due to this slope, the pipes
require a notable area of free space, extending over the entire
length of the engine and part of its height, avoiding this way
that the pipes obstruct the required
space for accessing the crank- case doors and compartments,
during maintenance work.

Illustration  2

shows,  on  the  right  side,  the  installation  of  a

VISATRON

®

oil  mist  detector,  type  VN215,  with  individual

compartment  suction  pipe  system  consisting  of  a  space-sa-
ving siphon block assembly set. The advantage of horizontal
pipe installation can be clearly recognised. Oil that precipita-
tes in the suction pipes is led back into the crankcase through
the siphon blocks. On the left side, in the conventional layout,
the unfavourable displacement of the suction points downwards
can be recognised.

Illustration  3

shows  a  further  alternative  in  tubing  arrange-

ment for VN115/87plus and VN116/87plus. To avoid collection
of excessive oil in the horizontal tubing system, oil separation
units are installed (see marking).

Illustration 4

shows the sectional view through a suction head

with its labyrinth, which effectively prevents spray oil from get-
ting into the suction pipe system.

suction pipe system consisting

of a space-saving siphon block assembly set. The advantage of hori-
zontal pipe installation can be clearly recognised. Oil that precipitates
in the suction pipes is led back into the crankcase through the siphon
blocks.  On  the  left  side,  in  the  conventional  layout,  the  unfavourable
displacement of the suction points downwards can be recognised.
Illustration 3 shows a further alternative in tubing arrangement for
VN 115/87plus and VN 116/87plus. To avoid collection of excessive
oil in the horizontal tubing system, oil separation units are installed

Illustration 1

Illustration 2

Illustration 3

Illustration 4

Page 7

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OIL MIST DETECTORS

Fitting  components  for  conventional  suction  pipe  sys-
tems.

(Illustration 5)

The engine wall connections join the labyrinth suction heads
located inside the crankcase compartment and the suction pi-
pes on the outside, and are available in various designs with
different metric or pipe thread sizes. Labyrinth suction heads
with different pipe lengths can be installed

(see Illustration 4)

. The engine wall connections can be used

for  conventional  suction  pipe  systems  or  also  in  connection
with  VISATRON

®

siphon  blocks. Engine  adapted  installa-

tion SAB  has  developed  various  types  of  VISATRON

®

as-

sembly units, in order to adapt to the installation conditions on
almost every engine design. The assembly units consist of  a
VISATRON

®

OMD, a specifi c engine adapted bracket,  avai-

lable  for  crosshead  and  trunk  piston  engines,  an  integrated
protective cover, an air pressure regulation unit, fi xtures and
fi ttings for the compressed air supply. The assembly unit is a
component  of  the  VISATRON

®

assembly  set.  SAB  supplies

special, ready-made modular assembly sets for VISATRON

®

oil mist detectors, for a variety of engine types from worldwi-
de manufacturers.  An oil mist detection system for a specifi c

engine, (Illustration 6) consists of:

The assembly unit  with oil mist detector

The pipe connections, either with engine wall connections

or siphon blocks

The ready-made pipes

All necessary fi tting material, such as pipe supports and

fastening elements

SAB  offers  a  special  design  service,  set  up  for  the  VISA-
TRON

®

adaptation to the engine for quick assembly, that is

available to all our clients.
Service Box

(Illus. 7)

on request The service box contains

all replacement parts, tools and devices necessary for the in-
itial operation, the repair and the fi xing of malfunctions. The
amount of replacement parts in the service box is designed in
such a way that a stock of replacement parts is available for
an  operating  period  of  one  year. Pressure  regulation  unit

(Illus. 8)

The pressure regulation unit consists of a precisio

pressure regulator and a throttle block with an integrated air
fi lter.  The throttle block ensures that the drive air pressure in
the VISATRON

®

oil mist detector does not increase to an ex-

cessively high level if the pressure regulator fails, (e.g. failure
of diaphragm). The pressure regulation unit is delivered, pre-
assembled and ready to operate, with its bracket.

VISATRON

®

assembly system

SCHALLER AUTOMATION

INDUSTRIELLE AUTOMATIONSTECHNIK GMBH & CO. KG

Illustration 5

Illustration 6

Illustration 7

Illustration 8

Page 8