Danfoss VACON NX Commissioning And Maintenance Manual page 19

INTRODUCTION
The temperature of the liquid going to the main drives must never be lower than the ambient
temperature in the cabinet at the point of a start-up of the main drives. If the system is shut down
during a cold period and the liquid runs a risk of freezing, a maximum of 20% of glycol can be added
to the primary circuit system. If more glycol than 20% is needed to keep the liquid from freezing then
contact your local distributor for additional information regarding a load reduction for the main
drive.
To prevent corrosion, add the corrosion inhibitor Cortec VpCI-649 to the primary circuit liquid. Use
the additive according to the product specification found in the Component Specifications and
Maintenance Instructions section of the Commissioning and Maintenance folder.
Pr imar y cir cuit liquid qual ity
pH
Hardness of liquid
Conductivity
Chlorine, Cl
Iron, Fe
Maximum particle size
Table 4.3-1, Liquid quality
The secondary circuit liquid quality is not expected to be as clean as the primary circuit liquid
bearing in mind that clean liquid will prolong the time between cleaning the plate heat exchanger
(HX11). If the customer and/or end-user are using a natural source of water for the secondary
circuit, one can assume that the water will include some kind of organic sediment. This organic
sediment will attach itself to the plates inside the HX11 and therefore the liquid-to-liquid heat
transfer between the primary circuit and the secondary circuit will, over time, be less efficient.
Another problem with this organic sediment is that the pressure loss over the HX11 will also
increase and therefore the flow will decrease, which will also lead to poor liquid-to-liquid heat
transfer between the primary and secondary circuit.
Because of possible organic sediment in the liquid circulation, it is strongly recommended that flow
measuring equipment or a pressure difference measurement be installed on the secondary circuit.
This equipment should generate an alarm if the flow is below requirements. When there is a need to
clean the heat exchanger, refer to the Alfa Laval, AlfaCaus, Heat Exchanger Cleaning material found
in the Component Specifications and Maintenance Instructions section of the Commissioning and
Maintenance folder.
In the secondary circuit, the liquid should not contain particles larger than 2 mm. If there are larger
particles in the liquid circulation, the 3-way valve or the heat exchanger might clog within a short
period of time. Therefore it is strongly recommended that a filter (MF21) be installed at the
secondary circuit inlet, which will filter out particles larger than 2mm. For more information
regarding this filter unit please contact our local distributor.
The secondary circuit liquid should not include any chemical residue that might be harmful for the
material used in the HX-unit e.g. high amounts of chloride, chlorine, oil etc. The HX-unit with the
PVC-C pipes uses EPDM rubber seals that will deteriorate if they come in contact with oil.
Local contacts: http:/ / dr ives.danfoss.com/ danfoss- dr ives/ local - contacts/
Unit Val ue

< 10
dH

< 10
S/cm
mg/l < 10
mg/l < 0,1

< 300
m
VACON 1 9
4