Ulvac CRYO-U Series User manual

CRYOPUMP
CRYO-U® SERIES
Instruction Manual

ＣＲＹＯ−Ｕ®４Ｈ





Export Control Policy
Vacuum pumps that pump nitrogen gas at pumping speed of 15000L/s or
more fall under row 2(35) of appended table 1 of Japan’s Export Trade
Control Order, which is based on international export control regimes.
Also, when applying a refrigerator system to a cryocooler for optical
sensors, the cryocooler falls under row 10(2) of appended table 1 of Japan’s
Export Trade Control Order as well.
Customers must follow all related rules and regulations such as Foreign
Exchange and Foreign Trade Act and take appropriate procedures when
exporting or re-exporting those products.
D/N.MA04A00E, 2017NR10 ULVAC CRYOGENICS INCORPORATED

MZ0F001E,2013OR03 ULVAC CRYOGENICS INCORPORATED F-1
Introduction
Thank you for choosing our products. This instruction manual gives
information and precautions on handling, installation, operation, and
maintenance of the product.
This product is intended for use by qualified personnel who recognize shock
hazards and are familiar with the safety precautions required to avoid possible
injury. To ensure proper use of this product, read this instruction manual
carefully and keep this manual close at hand so that you can use for reference
during operation.
If you purchased our other products and/or optional devices with this product,
read relevant instruction manuals carefully.
1. About the personnel who are involved in handling our products
All personnel involved in handling our products should take a general safety
education and training that is officially accepted in the country where our product
is used. The personnel are also required to have specialized knowledge/skills and
qualification on the electricity, the machinery, the cargo handling, and the vacuum.
Especially, the personnel should be familiar with handling a cryopump in order to
use it safely. Since we offer a training session (which is subject to fees) as needed
for people who use cryopumps for the first time, please do not hesitate to contact
our Service Engineering Division to join the training session.
2. Warranty
2.1 Gratis warranty period and Warranty coverage
【Gratis warranty period】
Note that an installation period of less than one year after installation in your
company or your customer’s premises or a period of less than 18 months (counted
from the date of production) after shipment from our company, which is shorter, is
selected.
【Coverage】
(1) Failure diagnosis
As a general rule, diagnosis of failure should be done on site by customer.
However, ULVAC CRYOGENICS or our service network can perform this service
for an agreed fee upon the customer’s request. There will be no charge if the cause

F-2 ULVAC CRYOGENICS INCORPORATED
of the breakdown is found to be a fault of ULVAC CRYOGENICS.
(2) Damage during transportation
When damage by delivery/transportation is admitted, the product will be
repaired free of charge within the range of the guarantee expressed in the sales
contract.
(3) Breakdown repairs
There will be a charge for breakdown repairs, replacements and on-site visits
for the following seven conditions. In those cases the cost shall be your own
expense even though the product is within the warranty period.
①Breakdowns due to improper storage or handling, careless accident, software
or hardware design by the customer.
②Breakdowns due to modifications of the product without consent of the
manufacturer.
③Breakdowns due to maintenance of the product without authentic parts or
breakdowns resulting from using the product outside the specified
specifications of the product.
④Breakdowns due to contamination or corrosion caused by user’s use
conditions.
⑤Breakdowns due to natural disasters (such as fire, earthquake, flood,
lightning, salt damage, and so on) , environmental pollution, irregular voltage,
and /or usage of undesignated power source.
⑥Breakdowns that are outside the terms of warranty.
⑦Consumables and/or replacement service.
Since the above services are limited to within Japan, diagnosis of failures, etc are
not performed abroad. If you desire the after service abroad, please contact
ULVAC CRYOGENICS and consult us for details in advance.
2.2 Exclusion of opportunity loss from warranty liability
Regardless of the gratis warranty term, compensation to opportunity losses
incurred to your company or your customers by failures of ULVAC CRYOGENICS
products and compensation for damages to products other than ULVAC
CRYOGENICS products and other services are not covered under warranty.

MZ0F001E,2013OR03 ULVAC CRYOGENICS INCORPORATED F-3
2.3 Repair period after production is discontinued
ULVAC CRYOGENICS shall accept product repairs for seven years after
production of the product is discontinued.
3. Service Form
After the products are delivered, please fill out the following information in the
blanks. If you have any questions or technical problems, please feel free to contact
the nearest Customer Support Center or headquarters. Please refer to “Service
Network”.
Cryopump／Super trap Model ：
Cryopump／Super trap Serial No. ：
Refrigerator Model ：
Refrigerator Serial No. ：
Compressor Model ：
Compressor Serial No. ：
Temperature controller／Thermal display Model ：
Temperature controller／Thermal display Serial No. ：
Option Part Model ：
Optional Part Serial No. ：
4. Notes for repair and maintenance requests
We may decline your request for the repair or the maintenance of our products if
you refuse to give us information about the presence of the hazardous substance
and/or contaminant.
Also, please be aware that we do not accept liability for damages by the
contaminant, which might be caused during transportation to our office or the
nearest customer support center. To avoid such accident, please pay careful
attention to packing of the product
5．In case of breakdown and accident
When breakdown or accident occurs, we may ask for keeping the product on site
as it is or retrieving the product to investigate its cause. Also we may ask for
reporting the detailed process and/or the operating condition. When unidentified
malfunction was generated, please contact our Service Engineering Division or

F-4 ULVAC CRYOGENICS INCORPORATED
the nearest customer support center with reference to the chapter of Service
Network. We ask for cooperation about the above.
6．General Precautions
(1) It is strictly prohibited to duplicate, open, and transfer this instruction
manual or any of its parts to a third person without written permission from
ULVAC CRYOGENICS.
(2) Information in this document might be revised without a previous notice for
the specification change and the improvement of the product.
(3) If you have any questions or comments on this document, please do not
hesitate to contact us. The phone numbers of local customer support centers
are listed at the end of this manual.

MZ0F001E,2013OR03 ULVAC CRYOGENICS INCORPORATED F-5
Safety Considerations
Our products have been designed to provide extremely safe and dependable operation
when properly used. Following safety precautions must be observed during normal
operation and when servicing them.
CAUTION
WARNING
A warning describes safety hazards or unsafe practices
which could result in severe injury or loss of life.
Acaution describes safety hazards or unsafe practices which
could result in personal injury or equipment damage.
Toxic gas or chemicals used.
There is a risk of severe injury upon contact.
Corrosive chemicals used.
There is a risk of severe injury upon contact.
Flammable gas used.
There is a danger of fire or burn injury.
Explosive gas used.
There is a risk of fire or explosion.
Hazardous voltage .
Electric shock may cause severe injury or loss of life.
Hot heating part present.
There is a risk of burn injury.

F-6 ULVAC CRYOGENICS INCORPORATED
This page intentionally left blank

CRYO-U®cryopump instruction manual
TABLE OF CONTENTS
Safety Instructions･････････････････････････････････････････････S-1
Disposal Consideration･････････････････････････････････････････ IW-1
CHAPTER 1 Cryopump Description
1.1 The General･･････････････････････････････････････････ 1-1
1.2 Specifications･････････････････････････････････････････ 1-2
1.3 Environmental Requirements･･････････････････････････ 1-3
CHAPTER 2 Inspection
2.1 Shipping List･･････････････････････････････････････････2-1
2.2 First Inspection of Cryopump･･･････････････････････････ 2-2
CHAPTER 3 Quick Installation･････････････････････････････ 3-1
CHAPTER 4 Installation
4.1 Auxiliary Equipments Required･････････････････････････4-1
4.2 Mounting the Cryopump to the Vacuum System･･････････ 4-3
4.3 Connecting Roughing Pump････････････････････････････ 4-5
4.4 Connecting Purge Gas Line･････････････････････････････4-5
4.5 Connecting Exhaust Pipe･･･････････････････････････････4-5
4.6 Connecting Cooling Water Pipe･････････････････････････ 4-6
4.7 Connecting the Cryopump to the Compressor Unit
(ConnectingFlexibleHoses)････････････････････････････4-6
4.8 Connecting Remote Wiring･････････････････････････････ 4-7
4.9 Connecting Electrical Cables･･･････････････････････････ 4-7
CHAPTER 5 Operation
5.1 Prior to Startup･･･････････････････････････････････････ 5-1
5.2 Rough Pumping･･･････････････････････････････････････ 5-1
5.3 Pressure Buildup Test･･････････････････････････････････5-2
5.4 Startup and Cooldown･････････････････････････････････ 5-2
5.5 Normal Operation･････････････････････････････････････ 5-3
5.6 Crossover･････････････････････････････････････････････ 5-4
5.7 Shutdown Procedures･･････････････････････････････････5-5
ULVAC CRYOGENICS INCORPORATED Ⅰ

Table of Contents
ⅡULVAC CRYOGENICS INCORPORATED
5.8 Handling of Hazardous Materials･･･････････････････････ 5-6
CHAPTER 6 Regeneration
6.1 The General･･･････････････････････････････････････････6-1
6.2 Regeneration Time････････････････････････････････････ 6-2
6.3 Warm-up Method･･････････････････････････････････････ 6-2
6.4 Regeneration Flow Chart･･･････････････････････････････6-4
CHAPTER 7 Disconnection and Storage
7.1 Disconnecting Flexible Hose････････････････････････････7-1
7.2 Storage･･･････････････････････････････････････････････ 7-2
CHAPTER 8 Maintenance
8.1 Scheduled and Unscheduled Maintenance･･･････････････ 8-1
8.2 Consumables･･････････････････････････････････････････8-3
8.3 Cleaning the Cryopump････････････････････････････････ 8-4
8.4 Charging Helium Gas･･････････････････････････････････8-5
8.5 Helium Circuit Decontamination･･･････････････････････ 8-8
APPENDICES
A. Troubleshooting･････････････････････････････････････････A-1
B. Flexible Hose･･･････････････････････････････････････････ B-1
C. Conversion of Thermometer Readings･････････････････････C-1
D. Principle of Cryopump Operation･････････････････････････D-1
E. Principle of Refrigerator Operation･･･････････････････････ E-1
F. Dew Condensation･･････････････････････････････････････ F-1
SERVICE NETWORK･･････････････････････････････････････････CS-1

CRYO-U®cryopump instruction manual
FIGURES
Figure 1-1Typical CRYO-U®Cryopump System････････････････････････1-1
1-2External Drawing of CRYO-U®Cryopump･･････････････････ 1-3
1-3 Major Components････････････････････････････････････････ 1-4
3-1Quick Installation Process Flow････････････････････････････ 3-2
4-1Example of CRYO-U®Cryopump Vacuum System････････････ 4-2
4-2Example of Cryopump Installation･･････････････････････････4-3
4-3Maintenance Space････････････････････････････････････････4-4
4-4Connecting Flexible Hose･･････････････････････････････････ 4-8
7-1Disconnecting Flexible Hose･･･････････････････････････････ 7-2
8-1Charging Helium Gas･････････････････････････････････････ 8-7
8-2Disconnecting Flexible Hose･･･････････････････････････････ 8-9
8-3 Connecting Charging Adapter･･････････････････････････････ 8-9
8-4 Cryopump Decontamination Procedures(1) ･････････････････ 8-10
8-5 Cryopump Decontamination Procedures (2) ･････････････････8-12
8-6 Connecting Flexible Hoses･････････････････････････････････ 8-13
D-1Vapor Pressure of Various Kinds of Gas･････････････････････D-2
E-1Principle of Refrigeration･･････････････････････････････････E-1
E-2Principle of G-M Cycle Operation･･･････････････････････････E-4
E-3Two-stage Refrigerator････････････････････････････････････ E-4
TABLES
Table 1-1CRYO-U®Specifications･･･････････････････････････････････ 1-2
1-2 Environmental Specifications･･････････････････････････････ 1-3
2-1 Shipping list for Cryopump system･････････････････････････ 2-1
2-2 Shipping list for Cryopump assembly･･･････････････････････ 2-1
3-1 Quick Installation･････････････････････････････････････････3-1
5-1Cryopump Temperature Indication･････････････････････････ 5-3
5-2 Maximum Quantity of Sucked Gas Processable by Cryopump･5-5
ULVAC CRYOGENICS INCORPORATED Ⅲ

Table of Contents
ⅣULVAC CRYOGENICS INCORPORATED
8-1Maintenance Parts and Intervals･･･････････････････････････ 8-2
8-2 CRYO-U®4H Consumables････････････････････････････････ 8-3
A-1Cryopump Fault Diagnosis････････････････････････････････ A-2
A-2Operating Log････････････････････････････････････････････A-7
F-1Dew-Point Temperature･･･････････････････････････････････ F-2

ULVACCRYOGENICSINCORPORATED S-1
Safety Instructions
The following precautions contain information regarding to safety of handling CRYO-U®
Cryopump. For employing it correctly and safely, please read these precautions carefully and
fully understand them before designing and setting up your entire pumping system with the
cryopump.
The cryopump is a pump of the type that captures gases and accumulates them up. In
the warm-up process during regeneration, the captured gases vaporize again and the
pressure in the cryopump is raised. The pressure changes depending on the kinds and the
amounts of the gases captured, as well as the size of the cryopump. For example, when
Argon is pumped up to its pumping capacity shown in the catalog, it becomes several
MPaG when converting into gas in the condition of the pump sealed up. To prevent an
explosion and/or destruction, CRYO-U®cryopump is provided with a pressure relief valve
which releases the increasing pressure.
The spring of the pressure relief valve is set to 10~20kPaG, and the valve opens when
the internal pressure exceeds this. Therefore please do not close the outlet of the pressure
relief valve, not strengthen the spring of the pressure relief valve, or not use it for other
purpose (for example, as a roughing port or a gauge port) because it is extremely
dangerous.
For handling the pressure relief valve, take notice to the following matters as well;
☆While the pressure relief valve is working, dust in the cryopump may cause a
leakage by sticking to the valve sheet. Clean the valve each time if used under
the condition that the pressure relief valve works at the time of regeneration. In
addition, remove and clean the valve regularly to avoid sticking of O-ring even
when it does not work.
☆For discharging a toxic or flammable gas, the quantity of captured gas should
be monitored and controlled so that the pressure relief valve should not open
at the time of regeneration. Also, it is surely required to install an exhaust duct
which is connected to the pressure relief valve in order to process the gas
safely. If using a toxic or flammable gas, please consult with us when
necessary.
1. Pressure Relief Valve

S-2 ULVAC CRYOGENICS INCORPORATED
Figure 1 Pressure Relief Valve (ULVAC CRYOGENICS products)
2. Confirm the safety of secondary-
generated gases in process
Some gases would be secondarily generated in vacuum processes. They might
ontain flammable gas, explosive gas, toxic gas, or combustion enhancing gas.
mentarily if there is a cause (refer to
“4
reaction with organic substances or any impact when it reaches in a high
co to confirm the safety of the secondarily generated gas as well
s that of process gases.
c
For example, water in vacuum chamber, which comes from the atmosphere or the
substrate, dissociates into hydrogen and oxygen in plasma. Those gases may be also
discharged in large amounts from some evaporants or sputtering targets. Oxygen is one of
the gases which increase the susceptibility to burn, and hydrogen is flammable and
explosive. At atmospheric pressure, the mixed gas of hydrogen of 4% or more and oxygen
of 5% or more are sure to cause the explosion mo
.When pumping flammable or explosive gases”).
In addition, ozone might be secondarily generated when oxygen(O２) or carbon dioxide
（CO２）is resolved in plasma. Ozone is a toxic gas，and moreover the liquid ozone might
explode by the
ncentration.
Therefore, it is necessary
a
For handling flammable or explosive gases, refer to “4.When pumping flammable or
explosive gases”and“5.When pumping oxygen” in this chapter. Implement safety precaution
and preventive maintenance as necessary.
For handling toxic gases, specific safety measures to the gas may have to be taken as

ULVACCRYOGENICSINCORPORATED S-3
well as the safety precautions for flammable or explosive gases. For example, purge of
pump or dilution of exhaust duct with inert gas corresponds to it.
opump operation according to an equipment and process where it
ill be adopted.
Table 1 Combu of major gases
(Volume percen ge against air)
Gas Molecular Weight 0℃
Boiling
Point Combustion Detonation
The customer oneself must execute the appropriate safety measure planning for
managing the cry
w
stion range and detonation range
ta

Specific
Gravity
, 1atm K Range
Vol. % Range Vol. %
Hydrogen
arbonC Monoxide
12.5-74.0
4.3-45.0
18.3- 59
Hydrogen
Sulfide
Silane*
Arsine*
Phosphine*
Diborane*
Ammonium
Methane
Ethane
Propane
Etylene
Acetylene 24
C2H226.04 0.907 198.2 2.5-100 4.2- 50
H2
CO
H2
S
SiH4
AsH3
PH3
B H62
NH3
CH4
C2H6
C3H8
C H
2.016
28.01
34.08
32.14
77.94
34.00
27.67
17.03
16.04
30.07
44.10
28.05
0.070
0.970
1.190
1.107
2.692
1.146
0.955
0.590
0.555
1.040
1.550
0.978
20.3
81.7
213.6
161.2
210.7
185.5
180.7
239.8
111.6
184.6
231.1
169.5
4.0-75.0
0.8-98
0.8-98
1.3-98
0.8-98
15-28
5.3-14
3.0-12.5
2.2-9.5
3.1-32
(*): Hikaru Harada; "Handotai-gas Anzen-ka Souran 1st Edition" (The 1st edition of Semiconductor
gas safing comprehensive manual) published by Science Forum Inc. 1984
The high pressure gas safety institute of Japan; "Koatsu-gas Kogyo GijyExcept (*): utu" (High pressure gas
industrial tech
Tabl mix am
Gas Combustion nge Detonation Range
nology) published by Kyoritsu Shuppan Co., Ltd. 1977
e 2 Combustion range and detonation range of
ture of oxygen and fl mable gas
Ra
(Vol. %) (Vol. %)
Hydrogen
Acetylene
oxide
2.3 - 94.5
15.5 - 94
Methane
Propane
Carbon Mon
Ammonium 15 - 79 25.4 - 75
4 - 94
5.1 - 61
2.3 - 55
15 - 90
3.5 - 93
-
3.7 - 37
38 - 90
The high pressure gas safety institute of Japan; "Koatsu-gas Kogyo Gijyutu" (High pressure gas industrial
chnology) published by Kyoritsu Shuppan Co., Ltd. 1977
te

S-4 ULVAC CRYOGENICS INCORPORATED
After stopping the cryopump operation, proceed with warm-up and rough pumping which
are parts of regeneration process in order to maintain the cryopump in a clean vacuum.
In many vacuum processes, a lot of moisture is often captured and condensed by the
cryopump. If the cryopump is left as it is after an operation stop, the captured moisture will
react with internal parts and cause corrosion.Moreover, when the corrosion of internal
parts becomes worse, it may bring about degradation of the pumping performance such as
prolongation of cooling time or rise-up of ultimate temperature as a result. Such corrosion of
inner kits occurs depending on not only moisture but also the kind and the amount of
process gas.
Therefore, make sure to perform regeneration immediately after the cryopump stops in
order to discharge water vapor. Following three steps in the regeneration sequence
mentioned in Section 6.4 are required; 1) Warm-up, 2) Discharge (desorption) of captured
gas, and 3) Pressure buildup check.
Please be aware that such corrosion of the inner kits might occur depending on the kind
or amount of the process gases, and note that when the part(s) needs to be exchanged due
to corrosion, part replacement is considered as fare paying service even if it is within the
term of a guarantee.
Hydrogen is a typical gas which has flammability and explosiveness. When a
flammable or explosive gas is pumped with the cryopump, it must be exhausted
safely from the pump in the warm-up process of regeneration. Be sure to take the
following safety precautions.
(1). Control and manage the process condition, the time period and method of
regeneration in order to keep the concentration of the hazardous gases
discharged to the exhaust duct below an allowable value.
(2). Eliminate ignition factors completely from the pump and duct.
(3). Make sure that the safety precautions mentioned above can work well even in any
abnormal events.
Possible causes of ignition in the vacuum equipment are the followings:
zIgnition by a vacuum gauge filament being turned on
zIgnition by a heater with heating element(s) exposed into the process
circumstance or the like
3. Proceed with regeneration right
after the cryopump stops.
4. When pumping flammable or
explosive gases 

ULVACCRYOGENICSINCORPORATED S-5
zIgnition by static electricity
zIgnition by liquid ozone
If a roughing pipe or and exhaust line is made of plastic such as vinyl chloride or etc., it
may produce static electricity.
On the other hand, ozone may generate under the process utilizing plasma with oxygen
or COX gas. Captured and condensed ozone in the pump liquefies in the warm-up process
of regeneration. Note here is the following. The liquid ozone is so unstable that it might
explode by impact or ignition resulting from the reaction with organic matter.
In case of a pumping flammable or explosive gas(es), appropriate safety precaution must
be taken with reference to “6. Regeneration after pumping flammable, explosive, or
combustion enhancing gas”.
5. When pumping oxygen
The mixed gas of oxygen and flammable gas should be very dangerous.
Oxygen is the gas that enhances combustion. Use the cryopump after
confirming the safety precautions or measures when pumping the mixture of
oxygen and flammable gas into the cryopump. In particular, the mixture of oxygen
and hydrogen, which has a broad range of combustion/detonation, is extremely
dangerous.
The mixes gas with hydrogen of 4% or more and oxygen of 5% or more at atmospheric
pressure could cause explosion momentarily (refer to “4.When pumping flammable or
explosive gases”).
Therefore, when oxygen is used as a process gas, the appropriate safety precautions
must be taken with reference to “6. Regeneration after pumping flammable, explosive, or
combustion enhancing gas”.
Oxygen may generate ozone.
Ozone may be unknowingly generated in plasma production process (e.g.,
sputtering, etching, glow discharge, EB deposition). Captured and solidified ozone in
the pump liquefies in the warm-up process of regeneration. The liquid ozone at high
concentrations might explode by impact or ignition by the reaction with organic matter.
In case that a remarkable amount of ozone is generated in the process and accumulated
in the cryopump, the following phenomena could be occurred around the pump at the initial
stage of regeneration:
①Cracking/popping sounds (as in electrical arching) occurring within the first few

S-6 ULVAC CRYOGENICS INCORPORATED
minutes of regeneration.
②Gas exhausted from cryopump during regeneration has a pungent odor, similar to
that produced in arc welding operation.
A lot of ozone causes an intense explosion, and is very dangerous. In case of
pumping ozone by the cryopump, the following safety precautions must be taken.
1. Suppress the amount of ozone captured in the pump below an allowable value by
increasing the frequency of regeneration. A required regeneration cycle depends on
the flow rate of oxygen gas and other process conditions.
2. Reduce the flow rate of oxygen gas to the minimum as far as it does not influence the
process performance.
3. Reconfirm the safety required if the process condition is changed, as it might increase
ozone yield.
When using oxygen as a process gas, appropriate safety precaution and measures must
be taken with reference to “6. Regeneration after pumping flammable, explosive, or
combustion enhancing gas”.


When regenerating the cryopump after pumping flammable, explosive, or combustion
enhancing gas, those gases must be safely vaporized again and exhausted. Following
safety measures on the regeneration method are extremely important for employing the
cryopump safely. Please take proper safety precautions and measures from both hardware
and process software points of view. Also, recognize there is a risk that some hazardous
gas would be secondarily produced in the vacuum chamber as a result of plasma reaction
or the like.
1. Safety measures for regeneration
Following are the safety measures which you should prepare and implement
regarding regeneration process after pumping flammable gas, explosive gas, or
combustion enhancing gas. Please take necessary measures referring to figure.2.
Moreover, you may have to take additional safety measures depending on the kind of
the gas used, the process conditions, or the environment used. Be sure to take
required and sufficient safety precautions according to actual conditions.
6. Regeneration after pumping flammable,
explosive, or combustion enhancing gas

ULVACCRYOGENICSINCORPORATED S-7
Figure 2 Dilution of Oxygen/Flammable Gas
①Whenever the cryopump has stopped regardless of causes of control order or power
failure, etc., it is necessary to immediately carry out the regeneration, which is
based on warm-up assisted with inert gas, in order to exhaust a flammable,
explosive, or combustion enhancing gas safely from the cryopump. For the
details of the regeneration, refer to “6.3 Warm-up Method” in Section 6. As for the
inert gas, use nitrogen gas that its dew point temperature is -40℃or below or argon.
(In this instruction manual, the words “inert gas” or “dry nitrogen or argon” mean
“nitrogen gas that its dew point temperature is -40℃or below or argon”.)
Both the purge of the cryopump and the dilution of the exhaust duct with the inert gas
are required for reducing the hazardous gas within the concentration where it does
not burn or explode even if it evaporates during warm-up.
Please fix up the purge flow rate, the dilution flow rate, and regeneration time period
(which related with the pumping capacity of flammable gas) and take measures
required before starting the cryopump operation.
②When the above regeneration is delayed or it is not conducted, all the gases captured
in the cryopump will be evaporated by natural temperature rise. After that, cryopump
pressure may reach to the atmospheric pressure easily or exceed it easily
depending on the amount of captured gases.
At this moment, however, never do evacuation of the hazardous gases remained in
the cryopump by using a roughing pump. Because, there is a possibility that such a
IN
R
OUT
Dilu t ion
Inertgas
Pressurereliefvalve
CRYO -U
Chambe r
Ou tdoo r
- Use metallic pipe and grounding.
- Determine the pipe diameter that can
prevent the pressure loss, considering the
length to the outside.
Exhaust line
Pressure relief valve
Chamber
CRYO-U®
Inert gas Inert gas
Outdoor

hazardous gas may explode in the roughing pump.
In order to exhaust the dangerous gas from the cryopump safely after
stopping the cryopump, be sure to purge them out to the exhaust duct with
inert gas before pumping by a roughing pump.
③Eliminate ignition factor. Insure that there are no sources of ignition (refer to “4. When
pumping flammable or explosive gases”) on the cryopump side during regeneration.
④Be sure to use metallic pipes for the roughing system and exhaust lines in order to
prevent generation of static electricity. Ground the pipes with the grounding
resistance of 100 Ωor less.
⑤In case that the gas to be exhausted is hazardous and lighter than the dilution gas
(such as hydrogen gas), design and install the exhaust pipes so that its lighter gas
should not be accumulated in the pipes.
⑥Perform inert gas purge into the exhaust line in order to reduce the flammable gas
concentration below its combustion range before exhausting them away to
atmosphere.
⑦Perform inert gas purge as the regeneration starts.
⑧Assuming the pressure relief valve would work, connect the pressure relief valve to
the exhaust line in order to dilute the gases which might spout out from the valve.
⑨Be sure not to rough pump the cryopump without inspecting the state of the pump
just after power failure. As mentioned in the above ②, reduce the concentration of
hazardous gases in the pump and exhaust line by adding inert gas before rough
pumping. It helps to exhaust the vaporized gas safely out of the pump in case power
failure occurred.
⑩When adopting a oil-sealed rotary pump as a roughing pump, change lubricating oils
with Fomblin grease which is insensitive to oxygen. Instead, a drypump will be fully
recommended.
2. Safety measures in emergency
If the troubles such as blackout, water outage, or pneumatic abeyance cause
suspension of a cryopump, take either among the following two actions.
1) When the cause of failure is eliminated before the temperature of the 2nd stage
reaches 20K, restart the cryopump.
2) When the temperature of the 2nd stage exceeds 20K, perform regeneration even if
the cause is eliminated. It is necessary to prepare some adequate devices to
introduce an inert gas automatically into both the cryopump and exhaust duct. The
devices include a thermometer, a valve for purge inert gas to the cryopump, a
S-8 ULVAC CRYOGENICS INCORPORATED