Section 6 - Commissioning; Preparation; Inspection; Refrigerant Charge - Quantech QTC4 STYLE A Series Installation Operation & Maintenance

Air-cooled screw liquid chillers with variable speed drive, 150 - 500 tons, 525 - 1750 kw, 2 compressor, 60 hz.

FORM QTC4-NM1

ISSUE DATE: 4/2/2018

PREPARATION

Commissioning of this unit should only

be carried out by Quantech Authorized

personnel.

Commissioning personnel should be thoroughly

familiar with the information contained in this docu-

ment before starting the unit.

The following basic checks should be made with the

customer power to the unit switched OFF.

Proper electrical lock out and tag out

procedures must be followed.

Inspection

Inspect unit for installation damage. If found, take

action and/or repair as appropriate.

Refrigerant Charge

Packaged units are normally shipped as standard with

a full refrigerant operating charge. Check that refrig-

erant pressure is present in both systems and that no

leaks are apparent. If no pressure is present, a leak test

must be undertaken, the leak(s) located and repaired.

Do not evacuate or liquid charge with static water in

the evaporator. Turn the pump on. Take care to liq-

uid charge slowly to avoid excessive thermal stress

at the charging point and to assure the refrigerant

temperature in the evaporator does not go below the

freezing point with liquid refrigerant in the evapo-

rator. Once the vacuum is broken, charge into the

evaporator or flash tank with the Condenser Drain

Valve (Flash Tank Feed) open and the chilled liquid

pump ON to the full operating charge, as detailed in

SECTION 5 - TECHNICAL DATA.

QUANTECH

SECTION 6 - COMMISSIONING

Correct System Refrigerant Charge

The charge on a system should always be checked

when operating for several minutes at full speed with

the system stable. Stable conditions are defined as

operation without fan cycling, economizer cycling, VI

solenoid cycling, or any other system transient condi-

tions. Ideal refrigerant charge will be reached when the

refrigerant level in the evaporator is near the middle of

the evaporator sight glass.

Service and Oil Line Valves

Open each compressor oil, economizer, and discharge

ball or service valves. If valves are of the back-seat

type, open them fully (counterclockwise) then close

one turn of the stem to ensure operating pressure is fed

to pressure transducers.

Compressor Oil

To add oil to a circuit - connect a hand oil pump

(Part No. 470-10654-000) to the 1/4" (6.35 mm) oil

charging valve on the oil separator piping with a length

of clean hose or copper line, but do not tighten the flare

nut. Using clean oil of the correct type ("L" oil), pump

oil until all air has been purged from the hose then

tighten the nut. Stroke the oil pump to add oil to the oil

system. While the compressor is running at full speed,

the oil level should be visible in the sight glass of the

oil separator. Approximately 2 to 3.1 gallons (7.5 to

11.6 liters) are present in each refrigerant system.

Refrigerant should not be added or

removed unless the level is at the bottom

or the top of the glass. It is not necessary to

weigh charge unless the entire charge has

been lost. The ease of charging is possible

since the microchannel coils hold only a

small amount of refrigerant charge. A

charging valve is located between the fixed

orifice and the evaporator for adjusting

charge. Charge should be added as liquid

with the pump ON and liquid flowing

through the evaporator.

Table of Contents

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