00193351-06_RI_Vacuum_pump_de en.pdf - 第54页
2 Retrofit instructions for vacuum pump SIPLACE HS-50/HS-60/D4/S-25HM/S-27HM/HF-Series 07/2011 Edition 52 The absolut e vacuum va lue in the h olding circuit wit h closed n ozzles is gener ally 30-50 mb ar lower for the …
SIPLACE HS-50/HS-60/D4/S-25HM/S-27HM/HF-Series 2 Retrofit instructions for vacuum pump
07/2011 Edition
51
2.6 Technical Information for retrofitting a vacuum
pump on HS60 / S27HM machines
The star of the DLM heads is moved to a parked position between two star steps where the hold-
ing and pickup circuits are connected via the vacuum distributor. 2
However, this means that the activated Venturi pickup circuit evacuates the thick vacuum hose via
the holding circuit (only when the vacuum pump is switched off) and within a period of a few min-
utes, draws water from the pump. The water serves as a sealant in the water ring pumps. The
series pump with sound-proof cover is therefore fitted with a non-return valve to prevent this and
an intake air filter to prevent contamination of the pump. 2
For this reason, the pump should always run when the machine is switched on. 2
Mutual influences of several machines on one pump: 2
The parked position connects the pickup and holding circuits. This means that the there is a mu-
tual influence between the vacuum circuits of the different machines, because all the holding cir-
cuits are interconnected.
For this reason, all machines must always be running if they are operated with a vacuum pump.
This ensures that the Venturi pickup circuit maintains the vacuum. 2
If individual machines connected to the same pump are to be switched off, a stop cock must be
introduced into the vacuum infeed.
It is generally recommended that a stopcock is incorporated upstream of each machine.
If this is not done, air is drawn in backwards through the silencer via the deactivated pickup circuit
by the other machines over the vacuum hose of the pump. This leads to a reduced vacuum. 2
Only if the nozzles of all heads are in a vertical position when the machine is switched off do the
machines not influence each other if no stopcock is fitted. 2
Checking whether the holding circuit vacuum system is airtight after retrofitting: 2
Procedure: Measure the vacuum with an external pressure gauge at the measuring point of the
vacuum distribution block and then at an open nozzle in the holding circuit of the head. 2
The difference should be no more than 20-30 mbar if everything is airtight. 2
If, however, the vacuum is tested in the holding circuit with closed nozzles, a different value can
be shown if an offset has been defined in the vacuum board. For this reason, it is sensible to carry
out the measurements at the head and the vacuum distributor with the same gauge. 2
2
2
2 Retrofit instructions for vacuum pump SIPLACE HS-50/HS-60/D4/S-25HM/S-27HM/HF-Series
07/2011 Edition
52
The absolute vacuum value in the holding circuit with closed nozzles is generally 30-50 mbar
lower for the vacuum pump than the vacuum value for the Venturi generator in the pickup circuit
(if each are measured with an external gauge on an open nozzle in the pickup circuit and on an
open nozzle in the holding circuit).
The absolute value is, however, not of great significance provided that it is in excess of 800 mbar
in Munich and all the heads have approximately the same value. 2
If these values are not achieved, it is almost always because a hose is not pushed firmly home.
The hose which is not airtight can be quickly detected by simultaneously squashing the hoses and
having a second person press the "Measure vacuum" button in the "Placement and pickup circuit"
field. 2
Checking the flow rate of the holding circuit vacuum system after retrofitting: 2
The correct flow rate can be checked with the vacuum curve.
To do this, SITEST is used to open each segment in the pickup circuit in turn without nozzles
(maximum flow rate) and then rotate the segment into the holding circuit with one star step. 2
Depending on the pump size and the number of machines connected, the vacuum measurement
in the holding circuit shows a decrease in vacuum of approx. 60-90 mbar for each additional open
nozzle. All heads should have similar values. 2
The vacuum could, for instance fall by 360 mbar from 880 to 520mbar if 6 nozzles are open. If
several machines are connected to a pump, the reduction is greater, and if only one machine is
connected, it is smaller. 2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
SIPLACE HS-50/HS-60/D4/S-25HM/S-27HM/HF-Series 2 Retrofit instructions for vacuum pump
07/2011 Edition
53
2.7 Final tasks
2.7.1 Check the pre-conditions for switching on
2
Before switching on make the following checks to avoid injury and damage. 2
2
2
Switch on always first the vacuum pump, then the placement machine! 2
Ensure before engaging compressed air, that 2
: all hoses / -connections are connected and allocated correctly.
: the pre-conditions for switching on vacuum pump and placement machine are followed, as
described in the user manual.
2.7.2 Check of holding circuit
2.7.2.1 Check vacuum system of holding circuit for pressure tightness
Vacuum measuring with external pressure measurement tool at the measuring point of the va-
cuum distributor and then an open nozzle at the holding circuit on the placement head. 2
The difference should not be higher than 20-30 mbar, if the system is tight. 2
At vacuum check of holding circuit a different value is possible, if vacuum board has an offset.
Therefore measurements at head an vacuum distributor should be done with the same measuring
tool. 2
2
The absolute vacuum value of holding circuit with closed nozzles is lower (30-50 mbar ) with
vacuum pump than with venturi nozzle in pickup circuit (measured with an external measurement
tool at open nozzle in pickup circuit and holding circuit) .
This difference is acceptable, if at a height of 521 m NN (height of System acceptance of Siemens
L&A Munich) at least 800 mbar can be achieved. 2
2
2
2
2
2
2
2