SPX Cooling Technologies TG MAG86-100, TG MAG185-125, TG MAG15-50 Maximum temperature of internals

3.10.2 Maximum temperature of internals

For some material combinations the general temperature performances must be limited. The maximum allowable working temperature of internals depends on the combination of materials used and their thermal expansions and the interference fit to hold the bearing bush fixed.

•Some bush bearings have an extra locking screw. In this case the maximum allowable tempera- ture is based on the most probable interference fit.

•In case the bearing bush has no locking screw because material and construction do not allow concentrated stress the maximum allowable temperature is based on the minimum inter- ference fit.

Maximum temperature (°C) of idler bush bearing material and idler material combinations

TG MAG pump						Bush and Idler materials (°C)
		Cast iron idler G					Steel idler S				Stainless steel idler R
size
	SG*)		CG	BG	HG	SS*)	CS	BS	HS	US	BR	CR	HR	UR
15-50	300		280	240	240	300	250	300	200	240	300	250	200	240
23-65	300		300	250	240	300	280	300	200	240	300	280	200	240
58-80	300		300	250	240	300	280	300	200	240	300	280	200	240
86-100	300		300	250	280	300	280	300	240	240	300	280	240	240
185-125	300		300	250	300	300	280	300	260	240	300	280	260	240

*) Remark: Hardness diminishment of steel bush (S) and hardened steel pin (2) above 260°C

The maximum allowable temperature of the rotor shaft bearing assembly is 280°C.

3.10.3 Operation under hydrodynamic lubrication conditions

Hydrodynamic lubrication could be important criteria for bush material selection.

If the bush bearings are running under the condition of hydrodynamic lubrication there is no more material contact between bush and pin or shaft and the lifetime cycle is increased significantly.

If there is no condition for hydrodynamic lubrication, the bush bearings make material contact with pin or shaft and the wear of these parts is to be considered.

The condition of hydrodynamic lubrication is fulfilled with the following equation:

Viscosity * shaft speed / diff.pressure ≥ K.hyd with: viscosity [mPa.s]

shaft speed [rpm] diff.pressure [bar]

K.hyd = design constant for each pump size.

TG MAG pump size	K.hyd
15-50	6250
23-65	4000
58-80	3750
86-100	3600
185-125	2500

3.10.4 Maximum torque of pump shaft and rotor material combination

The maximum torque is limited by the maxium transmittable torque of the magnetic coupling. This means the magnetic coupling will slip through before the rotor shaft or pump shaft reach their mechanical limitations.

A.0500.551 – IM-TGMAG/02.00 EN (02/2008) 19