background image

DHR/AR Series Environmental Test Chamber Getting Started Guide

Page 30

Operating Hints

Although the response time of the temperature control system is rapid, many of the samples that are of 
interest at high temperatures (

e.g

., bitumen, molten polymers, etc.) are very poor conductors of heat. 

Therefore, the limiting factor in reaching the desired starting temperature is the time it takes for the heat to 
be conducted into the sample and for the sample to reach thermal equilibrium. You can investigate a sam-
ple by carrying out an experiment using no equilibrium time and doing a time sweep experiment (in oscil-
lation mode). If you plot a graph of how the properties of the sample vary with time, you can quickly 
establish the required equilibrium time. 

The tendency of polymers (which are measured while in their molten state) to oxidize can present an addi-
tional complication. This problem is generally sample-dependent, but can be reduced by surrounding the 
sample with an inert atmosphere. To do this, use nitrogen gas rather than air as the feed to the ETC. It also 
helps if you optimize your test procedures to minimize the amount of time that the sample is held at high 
temperatures. 

Make sure the upper geometry is in place and free to rotate when you perform procedure for mapping of 
the bearing. For best results, perform the mapping procedure at ambient temperature and without purge gas 
flowing. 

Controlling Cooling

When you set the control valve on the liquid nitrogen unit, you must compromise between the rate of cool-
ing (which is improved by having a large flow rate) and the fineness of control (which is optimized when 
there is minimal flow rate from the needle valve.) When only a small amount of cooling is required, the 
solenoid valve is able to open and shut frequently. However, if a large surge of coolant occurred every time 
the solenoid valve opened, the system temperature would oscillate on either side of the set point. 

The setting of the needle valve is affected by the desired set-temperature: 

If cooling is needed at only a few degrees below ambient, then a very small opening is all that is neces-
sary. 

If you operate at -100°C, then a correspondingly higher flow rate of nitrogen is required. 

As a general rule, the correct needle valve setting for the desired temperature is one that results in the open-
ing and closing of the solenoid valve for more or less equal periods. Start with a setting of “open two com-
plete turns” and experiment to find the optimum position for your work experiment procedures. 

Low Temperature System Maintenance

For maintenance instructions of the cryogenic pressure vessel, please refer to the instructions supplied with 
the unit. If you purchased the Dewar flask from TA Instruments, the document is titled “Guide to good 
housekeeping, maintenance and periodic examination of cryogenic pressure vessels.” 

Содержание DHR Series

Страница 1: ...Revision D Issued November 2013 Getting Started Guide DHR Series and AR Series Environmental Test Chamber...

Страница 2: ...erty covering subject matter in this document Except as expressly provided in written license agreement from TA Instruments the furnishing of this document does not give you any license to these paten...

Страница 3: ...A Instruments Manual Supplement Please click the TA Manual Supplement link to access the following important information supplemental to this Getting Started Guide TA Instruments Trademarks TA Instrum...

Страница 4: ...A C22 2 No 61010 2 010 Particular requirements for laboratory equipment for the heating of materials For European Economic Area In accordance with Council Directive 2006 95 EC of 12 December 2006 on t...

Страница 5: ...uency Generators For the European Economic Area In accordance with Council Directive 2004 108 EC of 15 December 2004 on the approximation of the laws of the Member States relating to electromagnetic c...

Страница 6: ...lowing label is displayed on the accessory for your protection Please heed the warning labels and take the necessary precautions when dealing with these areas This Getting Started Guide contains cauti...

Страница 7: ...the Environmental Test Chamber ETC 8 ETC Components 9 The ETC Viewer 10 System Specifications 11 Chapter 2 Installing the ETC 12 Installing the ETC Assembly on the DHR Series 12 Mounting the Test Cham...

Страница 8: ...n unit for the DHR AR G2 AR 2000ex that enables it to characterize solid samples in torsion To work on composites polymers in torsion requires a temperature controlled chamber for envi ronmental contr...

Страница 9: ...see Figure 2 Various interlock devices are fitted for safety purposes These devices detect the position of the doors The Status Bar in TRIOS software reports the current state open partly open or clos...

Страница 10: ...with any USB camera so a web cam can be easily used for Peltier tests The viewer assembly is air cooled to allow it to perform over whole temperature range of the ETC 160 to 600 C WARNING After ETC u...

Страница 11: ...a time sweep or peak hold test with the temperature set if possible to a few degrees in excess of the end temperature Set the time much longer than you expect the test can be aborted when the temperat...

Страница 12: ...r and move the rheometer head up to the maximum height Use the Head Up button located on the instrument control panel 2 Turn off the power to the rheometer control box 3 The ETC is most easily fitted...

Страница 13: ...C with the doors fully open using the handles as shown below Figure 4 Lifting the ETC door 6 Insert the dowel pins on the ETC into the dowel holes on the rear of the instrument as shown in Figure 5 Fi...

Страница 14: ...position with the doors still fully open the ETC will self support on the dowel pins Figure 6 ETC mounted on back of instrument with doors fully open 8 Screw the four captive screws into the casting...

Страница 15: ...to the Attachment Left and Attachment Right Figure 8 Attachments installed on rear of instrument 10 Open the ETC oven door to gain access to the Smart Swap mounting Removal of the ETC is the reverse o...

Страница 16: ...aximum height Use the Head UP button located on the instrument control panel 2 Fit the air bearing clamp to the rheometer 3 Turn off the power to the rheometer control box 4 Ensure that the two top sc...

Страница 17: ...the ETC on the rheometer 9 Connect the two cables on the ETC to the attachment connectors on the rheometer as shown in the figure below 10 With the ETC oven doors open gain access to the Smart Swap m...

Страница 18: ...the rheometer 3 Close the oven and ensure that no part of the doors touch any part of the lower fixture No change should be observed in the axial force when the doors are closed Adjust the position o...

Страница 19: ...L min flow rate it is recommended that you connect the feed gases to the ETC as shown in Figure 15 Otherwise connect as shown in Figure 14 below CAUTION The reducing valve is factory set to 10 L min...

Страница 20: ...DHR AR Series Environmental Test Chamber Getting Started Guide Page 20 Figure 15 ETC connections using nitrogen as the agitation gas...

Страница 21: ...llowing additional steps to complete the installation 1 ConnecttheEventcablefromtheCCUflowcontrolassemblytotheEventAconnectionontherheometer Figure 16 Event connection 2 Ensure that the cryogenic syst...

Страница 22: ...Connect the cable from the Liq connector on the flow assembly to the solenoid valve on the cryogenic system 6 Set a pressure of 15 to 20 psi on the Dewar system 7 Open the control valve approximately...

Страница 23: ...shop for repair follow these instructions NOTE The pictures shown are for the AR Series but the process is essentially the same for the DHR Series 1 Turn off power and air 2 Remove the two 3 mm hex h...

Страница 24: ...move the unit Fit the insulated plug in its place Figure 22 Removing the bulkhead screws 5 Remove the three 3 mm nuts holding the main viewer module in place and remove the unit Fit the insulated plug...

Страница 25: ...gure 24 Disconnecting power 7 The complete unit can now be removed and packed in its original packing material 8 Follow the instructions in reverse for fitting the viewer module Connecting the Camera...

Страница 26: ...2 Connect EXP 1 on the control box to EXP 1 on the rear of the main electronics box See the figure below Figure 26 Rear of main electronics box 3 Connect the video out to a USB adapter which is in tur...

Страница 27: ...mental Test Chamber Getting Started Guide Page 27 ETC Viewer Schematics The following figures provide schematics of the various components of the ETC Viewer Figure 28 Cooling schematic Figure 29 Prima...

Страница 28: ...DHR AR Series Environmental Test Chamber Getting Started Guide Page 28 Figure 30 Sample view Figure 31 Lighting schematic...

Страница 29: ...data When you use the parallel plates make sure that the oven thermocouple is not touching the plates When you use the parallel plates if you find that the lower plate is difficult to remove make sure...

Страница 30: ...the mapping procedure at ambient temperature and without purge gas flowing Controlling Cooling When you set the control valve on the liquid nitrogen unit you must compromise between the rate of cool i...

Страница 31: ...tandards 4 Environmental Testing Chamber ETC installing 12 installing the low temperature accessory 21 oven 16 setting up 12 equilibrium time 30 ETC control electronics 9 gas ring 9 heating chamber 9...

Страница 32: ...ber 9 I instrument symbols 6 L license agreement 3 low temperature accessory 21 M mapping procedure 30 N notes 4 O operation rheometer 30 oven 9 P parallel plates 29 cleaning 29 patents 3 polymers 30...

Страница 33: ...rted Guide Page 33 rheometer additional precautions 29 connecting the purge gas 19 cooling 30 thermocouple 29 S safety 6 instrument symbols 6 Safety Standards 4 safety standards 4 T TA Instruments off...

Отзывы:

Похожие инструкции для DHR Series