Vilter VSM 71-701 Operation And Service Manual Download

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October 2003 /

BULLETIN 10-11

Table of Contents

Installation

Valve Location  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Solder Techniques  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Bulb Location and Installation  . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
External Equalizer Connection  . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Driers, Strainers, and Accessories . . . . . . . . . . . . . . . . . . . . . . . . . 4
Test Pressures and Dehydration Temperatures  . . . . . . . . . . . . . . . 4
Expansion Valve Adjustment  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
How to Determine Superheat Correctly  . . . . . . . . . . . . . . . . . . . . 5
How to Change the Superheat Setting  . . . . . . . . . . . . . . . . . . . . . 5

Field Servicing

Complaint:
A

- Valve does not feed enough refrigerant . . . . . . . . . . . . . . . . . 6

- Valve feeds too much refrigerant . . . . . . . . . . . . . . . . . . . . . . 8

- Valve feeds too much refrigerant at start-up only . . . . . . . . . 8

- Valve doesn't feed properly . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

- System hunts or cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

- System won't perform properly . . . . . . . . . . . . . . . . . . . . . . 10

Field Assembly Instructions

. . . . . . . 10

Installation

For peak performance, it is important to select a Sporlan
Thermostatic Expansion Valve (TEV) with correct capacity, selective
charge, external or internal equalizer, etc. See Bulletins 10-9 and 10-10
for complete application information. Equally important is the proper
installation, which can determine the success or failure of the entire
system.

Valve Location

TEVs may be mounted in any position, but they should be installed
as close to the evaporator as possible. If a refrigerant distributor is
used with the expansion valve, best performance is obtained if the
distributor is mounted directly to the valve outlet. If the distributor
cannot be mounted directly to the valve outlet, the distance between
the valve outlet and distributor should not exceed 24 inches or refrig-
erant distribution problems may occur. Also, the tube connecting the
valve outlet and distributor can be sized smaller to maintain refrig-
erant velocity and better distribution. Elbows located between the
expansion valve and distributor will hinder proper distribution and
therefore, are not recommended.

Best distribution is usually obtained if the expansion valve feeds
vertically up or down into the distributor. System manufacturers,
however, have successfully applied distributors in other orientations.

See Bulletin 20-10 for application and selection information on
refrigerant distributors.

While not always convenient or possible, valve Types BI, F, FB, and
O are easier to service if mounted in a vertical and upright position.
If mounted in a horizontal position, the internal parts must be
carefully reassembled to prevent damage to them. Also, some consid-
eration should be taken in mounting larger sized expansion valves.
They must be adequately supported since system vibration and the
weight of the valve may cause valve connections to fracture.

If a hand valve is located on the outlet side of the TEV it should have
a full sized port. No restrictions should appear between the TEV and
the evaporator, except a refrigerant distributor if one is used.

Sporlan TEVs having Selective Charges C, Z, L, or X may be
installed and operated in most locations. The amount of thermostatic
charge and the bulb size are such that the bulb retains control despite
a colder valve body or diaphragm case. The exception is when the
element is subjected to sub-zero temperatures for extended periods of
time during an off-cycle. In this case, start-up may be prolonged until
the bulb and element are warmed sufficiently to open the valve.

To minimize the possibility of charge migration, the Sporlan MOP
type charges (CP series, ZP series, and VGA) should be installed so
the diaphragm case is warmer than the bulb. Special non-condensable
charges without MOP and double diaphragm hydraulic elements with
MOP are available for system manufacturers to overcome this
potential problem.

Occasionally, TEVs are located in corrosive atmospheric conditions
that can damage the valve and/or the element assembly. Due to this
possibility, the valve must be protected with appropriate materials to
prevent premature failure. Consult specialists in protective coatings.

Precautions:

When the evaporator and TEV are located above the
receiver

, there is a static pressure loss in the liquid line. This is due

to the weight of the column of liquid refrigerant, and this weight may
be interpreted in terms of pressure loss in pounds per square inch as
shown in Table 3, Bulletin 10-9. If the vertical lift is great enough,
vapor or

flash gas

will form in the liquid line causing a serious

reduction in the capacity of the TEV.

When an appreciable vertical lift is unavoidable, precautions should
be taken to prevent the accompanying pressure loss from producing
liquid line vapor. This can be accomplished by providing enough
subcooling to the liquid refrigerant, either in the condenser or after
the liquid leaves the receiver. Subcooling is determined by
subtracting the actual liquid temperature from the condensing
temperature (corresponding to the condensing pressure). A
subcooling calculation example is provided in the "subcooling"
section of Bulletin 10-9.

© Copyright 2003 by Sporlan Valve Company, Washington, Missouri
Bulletin 10-11, October 2003 Supersedes Bulletin 10-11, September 1996 and all prior publications.

Thermostatic
Expansion Valves

Installation, Field Service, and Assembly