mycom SCV Series User Manual

2205Q2JE-HO-S6-N_2020.01.
Chapter 4 Compressor and Package Unit Operation
SCV-series Screw Compressor 4.1 Adjustment of Vi
4-1
Chapter 4 Compressor and Package Unit Operation
4.1 Adjustment of Vi
4.1.1 Overview
The internal volume ratio Vi of SCV-series screw compressors has been adjusted as H port (5.8) at the
time of shipping.
Before starting the commissioning of the package unit, confirm the appropriate Vi of the compressor for
customer’s operating conditions and change the Vi setting if necessary.
When changing of the intended use of the compressor and/or there are large temperature changes of
seasons in usual operation of the package unit, confirm the properly of the Vi setting and change it if
necessary.
Changes in operating condition experienced in daily operation have no significant influence on the
shaft power. Therefore, it is not necessary to change the Vi setting that adjusted once to operating
conditions.
In addition, with a compressor that is used for a freezing system in which the evaporation temperature
varies between 0 and -30 °C as time passes, the Vi setting should not be changed according to the
change resulting from rises in compression ratio. In this example case, the compressor should be used
with the Vi fixed at M port setting.
 Fix the Vi setting and do not adjust it while the compressor is in operation.
In the case of a special application that requires frequent adjustment of the Vi to
match it with varying operating condition, it is recommended to use a
Maximizer screw compressor (produced by MAYEKAWA as another series product)
that incorporates a mechanism for hydraulically adjusting the position of the
variable Vi auxiliary slide valve.
 Do not operate the compressor with the Vi at any other setting than the L, M or H
port setting.
 In case of considering change from L port to H port or reverse, be sure to consult us
beforehand because it will be necessary detailed examination due to specification
of compressor’s unloader slide valve.
4.1.2 How to adjust the Vi setting
 Never perform Vi adjustments while the compressor is in operation. Perform Vi
adjustments only after stopping the compressor. Because the rotary shafts are near
the Vi adjustment location, there is an increased risk of personal injury or death as
clothing can be caught in rotating shafts or tools may get in touch with them.
Numbers enclosed in [ ] in following instructions means the part number in Section 7.1 "Exploded Views
and Sectional Views" and Section 7.2 "Parts Configuration Table" in this manual Chapter 7.
a) First, determine the expected operating condition of the system and work out the Vi value under the
condition thus determined (use the formula shown in Section 2.4.3.3 “Why the Vi Needs to Be
Changed?” for the calculation) in this manual Chapter 2.
Next, select the L, M, or H port setting, whichever is the closest to the calculated Vi value. The
compressor is set to the “H” port position before shipment.

mycom SCV Series Specifications

General

Brand	mycom
Model	SCV Series
Category	Air Compressor
Language	English