Cooling of NA62 vacuum systemNovember 11th, 2014

E. Harrouch, EN-MEF, on behalf of the NA62 Vacuum Team

Outline

Summary of the installation

History

Consequences of a water cut

EATM 2

3EATM

4EATM

Blue tube vacuum system

• DN250 Turbo group• Primary pumps• He Compressors (for cryo pumps)

EATM

Demineralized water network

Raw water network

Water cooling network

5

Current situation

EATM

• One accidental water cut (Wednesday 22th of October).

• One planned on Tuesday 28th of October.

• According to CV : You can expect around 5 water cut per year.

• Origin : Power cut, pressure drop (water leak, purge valve remained open …)

6

7EATM

Consequences

For the DN250 turbo group :No consequences as long as PBT < 10-3 mbar

Primary pumping group:No consequences if it does not happen during pump down

Cryo pumps:Compressor will stop, gate valve will close and cryo pump will enter into regeneration mode.

8EATM

• The cryo pumps will need one day to be cooled down again. At the moment, it requires a local intervention.

Consequences

9EATM

Risks

• For the turbo pump and primary pumping group : No particular risk.

• For the cryo pumps : In regeneration mode it requires nitrogen supply. If the power or nitrogen is missing. This could damage the cryo pump.

Vacuum envelope

P

T1

T2

Purge gas (N2) inlet with gas inlet heater Heating

jacket

Cryosorber

≈ 15 K

≈ 50 K

Roughing valve DN63

10EATM

• 3 water network available in the ECN3 cavern :• Demineralised water• Raw water• Fire brigade water network

How to make the system safer

11EATM

• No real advantage to switch from the demineralised water network to the raw water network. (same rate of failure)

• Use a similar system as it is done on the He Compressors in for COMPASS : Use of the drinking water network as backup.

How to make the system safer