Synrad Novanta 48 Series, Manual, Page: 39 / 89

COOLING PAGE | 39
(closed circuit). Power-On Reset is defeated on all OEM versions. OEM customers must provide this
required safety feature elsewhere as part of their equipment integration.
Cooling
Series 48 electronics are mounted opposite the laser tube in the smaller section of the “H” bay and share
the same cooling removal as the plasma tube. Typical efficiency of CO
2
laser plasma tubes operating in a
TEM
00
mode is 10% to 12% (radiation out to RF power in). Factor in the conversion efficiency of AC input
to RF output and the overall “wall plug” efficiency of these lasers drops to about 6% to 8%, resulting in a
considerable amount of heat removal, even at 10 W and 25 W output power levels; therefore, external
cooling in the form of forced air- or water-cooling is required.
Since Series 48-1, 48-2 lasers are OEM products, they do not include cooling fans. Customers must provide
some type of air cooling to prevent the laser from overheating. See the cooling requirements at the end
of this section.
Important Note
:
DO NOT use de-ionized (DI) water as a coolant. DI water is unusually corrosive
and is not recommend for mixed material cooling systems.
Coolants
NOVANTA recommends that the laser’s cooling fluid contain at least 90% distilled water by volume. In
closed-loop systems, use a corrosion inhibitor/algaecide such as Optishield® Plus or equivalent as required.
Avoid glycol-based additives because they reduce the coolant’s heat capacity and high concentrations
may affect power stability. For NOVANTA lasers, the minimum coolant setpoint is 18 °C (64 °F) so glycol
is not necessary unless the chiller is subjected to freezing temperatures. If tap water is used, chloride levels
should not exceed a concentration of 25 parts per million (PPM) and total hardness should be below 100
PPM. Install a filter on the chiller’s return line and inspect frequently.
Setting coolant temperature
Choosing the correct coolant temperature is important to the proper operation and longevity of your laser.
When coolant temperature is lower than the dew point (the temperature at which moisture condenses out
of the surrounding air), condensation forms inside the laser housing leading to failure of laser electronics
as well as damage to optical surfaces.
The greatest risk of condensation damage occurs when water-cooled lasers are run in a high heat/high
humidity environment and the chiller’s coolant temperature is colder than the dew point temperature of
the surrounding air or when the system is shut down, but coolant continues to flow through the laser for
extended periods of time.
The chiller’s temperature setpoint must always be set above the dew point temperature. In cases where
this is not possible within the specified coolant temperature range of 18 °C to 22 °C (64 °F to 72 °F), then
the following steps MUST be taken to reduce the risk of condensation damage.
• Stop coolant flow when the laser is shut down.
• Increase coolant flow by an additional 3.8 LPM (1.0 GPM). Do not exceed a coolant pressure of 414
kPa (60 PSI).