Charpy/Dynamic Tear Bath (-120 C - 200 C)
The MPM Circulated Charpy/DT Bath (CC/DTB) operates over a wider temperature range than can be obtained using refrigerant-cooled baths. The system operates over the temperature range of -120 C to 200 C. The MPM CC/DTB reaches cold setpoints faster because it uses liquid nitrogen as a coolant for tests that are conducted below room temperature.
The open tank which contains the test specimens is available in 11-liter or larger sizes. The standard system contains up to 63 Charpy impact test specimens. The Charpy specimen holders can be easily removed and replaced with dynamic tear (DT) specimen holders.
Charpy/DT Specimen Holder Racks
The MPM CC/DTB is provided with 5 Charpy racks unless otherwise specified. These racks are sold separately as replacements in case of loss or damage during handling. In addition, DT specimen holders can be ordered for the bath. It is very easy to change the bath from Charpy to DT testing.
When configured for Charpy testing, a handle is attached to each rack to raise the specimens to a level just beneath the surface of the fluid so that they can be held with Charpy centering tongs in the bath just prior to transfer to the impact test machine.
No Annoying Magnetic Stirrers
ASTM E 23 requires continuous agitation of liquid baths. Some bath manufacturers use magnetic stirrers which often freeze or stop spinning due to ice crystals in the bath fluid. The MPM bath is continuously circulated using mechanical means that never stop, even at low temperatures.
Easy Fluid Transfer in and out of Bath
The fluid is transferred into the bath by simply pouring the fluid into the specimen holder chamber. The system is also equipped with valves and piping so that the liquid heat transfer medium in the bath can be easily transferred into a container. This makes fluid change-out very convenient. A bath cover is provided to prevent the intrusion of dirt at times when the bath is not in use.
Easy Operation without Special Training
Operating the bath does not require any special training. The operator simply uses up-down arrows to set the desired test temperature. Fluid transfer out of the bath is achieved by simply opening a marked valve. The MPM CC/DTB comes with the option of a roll around cart. This cart allows for the bath to be moved easily, and places the top of the bath at the optimal height for testing.
Achieve Setpoint Temperatures Quickly
For tests conducted above room temperature, the 3,500 Watt heating system rapidly raises the temperature to the desired setpoint. Since liquid nitrogen is used as the heat transfer medium at low temperatures, the desired test temperature is reached in a fraction of the time required by refrigerated systems.
ASTM Standards and Precision
The MPM CC/DTB fully satisfies the requirements of ASTM Standard E23, “Notched Bar Impact Testing of Metallic Materials,” E208, “Drop-Weight Test to Determine Nil-Ductility Transition Temperature of Ferritic Steels,” and E604, “Dynamic Tear Testing of Metallic Materials.” The desired bath setpoint temperature is held within 1 C when the setpoint is attained and the bath is continuously agitated with at least 25 mm of fluid surrounding the test specimens.