Prentex 9900E User manual

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Operator’s Manual
Prentex Model 9900E
Vacuum Degassing Oven
Prentex Alloy Fabricators, Inc.
3108 Sylvan Avenue
Dallas, TX 75212-4096 U.S.A.
Tel: 800 - 728 - 3812; 214 - 748 - 7837
Fax: 214 - 748 - 7850
e-mail: [e-mail]
Prentex
ALLOY FABRICATORS, INC.
www.prentex.com
Prentex
ALLOY FABRICATORS, INC.
www.prentex.com
Prentex
ALLOY FABRICATORS, INC.
www.prentex.com
Prentex
ALLOY FABRICATORS, INC.
www.prentex.com
Model 9900E
Operator’s Manual
Vacuum Degassing Oven
3108 Sylvan Avenue Dallas, Texas 75212-4096 U.S.A.!
Tel: [phone] - 3812 Fax: [phone] - 7850 !
Email: [email protected]
Prentex
!

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Operator’s Manual for Prentex Model 9900E Vacuum Degassing Oven
Contents
Welcome from the manufacturer Page 1
1. Setting Up Your Model 9900 Page 2
2. O-Ring Gasket Information Page 2
3. Absolute Vacuum and Adjusting Your Prentex
Model 9900 Vacuum Degassing Oven’s Vacuum Page 2
4. Operating the Prentex Model 9900 Vacuum Oven Page 4
5. Changing the Preset Values –
Temperature, Time 1, Time 2 Page 6
6. Calibrating the Temperature Sensor Page 6
7. Calibrating the Vacuum Gauge Page 8
Spare Parts and Accessories Back of Manual
Calibration Certificate
Compressed Air
O-Ring Gasket Information
Page 2

Prentex Alloy Fabricators, Inc.
MEMORANDUM
To: Prentex Model 9900 Vacuum Oven Purchasers!
Subject: Operator’s Manual
Congratulations on your purchase of the Prentex Model 9900 Vacuum Degassing
Oven for the AASHTO and ASTM PAV Practice. After years of experience with the
Model 9900, this manual should be complete and accurate. If you discover any edits
or additions that may improve the usage, please feel free to send suggestions by
email to [email protected]!
!
If you have any questions regarding your new vacuum oven or about any Prentex PAV
Systems feel free to call us at 214-748-7838 or TOLL FREE at 1-877-PRENTEX
between 08:00 and 16:30 CST. You may also email: [email protected]; or should
you require, fax: [phone].
+1.877.PRENTEX!
Carolyn Wester, CEO!
Prentex
ALLOY FABRICATORS, INC.
www.prentex.com
Prentex
ALLOY FABRICATORS, INC.
www.prentex.com

Operator’s Manual for Prentex Model 9900E Vacuum Degassing Oven
Page -2-
1. Introduction and setup: Model 9900 Vacuum Degassing Oven
1.1 After removing the unit from its shipping carton, remove everything from the vacuum
chamber.
1.2 Connect the power cord to the receptacle in the back of unit and plug it in to a standard
110-125 v ac. 60HZ outlet [10 Amp or greater capacity].
[For export systems: 230-240 v ac., 50 Hz, 5 Amp capacity.]
1.3 Turn the power switch “On”. The control display should light up, with the word “idLE”
displayed, alternating with the current air temperature.
2. Install Main O-Ring Gasket
Place an orange O-Ring gasket (supplied with the PAV) in the groove on the flange and
then place the cover on the vacuum Oven.
A. The O-ring will tend to be too small until it heats slightly and expands to the groove’s size -- If it is too
small, stretch the O-Ring between two hands to get it to fit into the groove.
B. An alternative method to set the O-ring is to place the edge of the lid on the O-Ring and roll it into the groove as you
close the vessel.
Be aware that after several uses, the O-Ring, once seated correctly will tend to stay in the groove between uses and
will require little attention other than periodic cleaning.
Note: When the Vacuum Oven is heated, the O-Ring may expand and bulge out of the groove when the lid is removed.
Since it is important to have a properly fit O-ring, one solution is to cool the O-ring in water and place it back in the
grove (if it does not need cleaning or has not been pinched).
An alternate solution is to keep a spare O-Ring handy to replace in the grove.
2.1 Replacement O-Ring Information. An O-ring should be replaced when it will no longer shrink to normal size or has
been pinched in a manner to prevent it from expanding as necessary to seal the lid properly. The O-Ring gasket is
Parker size 2-274; desired material is Silicone Rubber. Viton may be used, but has less resiliency and it may be more
difficult to get a good vacuum seal.
2.2 Window O-Ring Gasket. The viewing window in the lid is also sealed by an O-Ring gasket. This gasket will probably
not require replacement unless you break the glass. A new O-Ring is furnished with replacement glass, but if required,
it is size 2-161, and the desired material is Silicone Rubber.
3. Absolute Vacuum and Adjusting Your Prentex Model 9900 Vacuum Degassing Oven’s Vacuum Pressure
Adjusting vacuum pressure requires awareness of the following:
3.1 The AASHTO PP-1 and ASTM D-6521 Standard Practice for Accelerated Aging of Asphalt Binder Using a
Pressurized Aging Vessel [PAV] specify degassing the PAV-aged samples at 15±2½ kPa absolute pressure [25.5 ±
0.74 in / Hg negative gauge pressure at standard atmospheric conditions].
3.2 Relative Pressure Vacuum Gauges. Vacuum gauges commonly used in the U.S. measure vacuum relative to the
local atmospheric pressure and express it as a negative number. Vacuum is indicated as a negative gauge pressure
below the ambient atmospheric pressure, measured by the amount of mercury supported in a manometer in inches [in
Hg] or millimeters [mm Hg], or the force exerted by the mercury column, expressed in kilopascals [kPa]
3.3 Thus, the vacuum level of ambient atmospheric pressure is “0" in negative gauge, whether in Hg, mm Hg or kPa. The

Operator’s Manual for Prentex Model 9900E Vacuum Degassing Oven
Page -3-
absolute pressure measurement at sea level and 15EC would be 29.92 in Hg, 760 mm Hg or 101.3 kPa. “Full
vacuum”, or no atmospheric pressure under these same conditions would be “0" whether expressed as in Hg, mm Hg
or kPa.
3.4 Problems arise in using a gauge that references relative atmospheric pressure to measure absolute pressure at
altitudes above sea level. As altitude increases, the atmospheric pressure exerted on the gauge drops. At sea level
and standard conditions, 15 kPa absolute can be referenced at -25.5 in Hg. However, at only 1,000 feet in altitude, the
targeted 15 kPa absolute occurs at a negative gauge pressure of approximately -24.4 in Hg. As altitude increases or
ambient barometric pressure changes. it can cause your degassing vacuum indicate that it is “out of spec” when it
actually “in spec” when corrected for ambient pressure.
3.5 The chart below gives approximate altitude conversions for barometric with altitude in feet in the first column and
barometric pressures indicated in the second and third columns in both in Hg and mm Hg. The negative gauge
equivalents of 15 kPa are provided in both in Hg and kPa in the last two columns.
3.6 Local weather and climatic conditions. Local weather and climatic conditions affect the actual barometric pressures for
any given location. Refer to your local weather bureau for true barometric pressure. Using the average local
barometric pressure may meet your requirements; however user should be aware that barometric fluctuations can
cause this “average value” to fall outside the allowed tolerance of ± 2.5 kPa [0.74 in Hg / 19 mm Hg ].
3.7 Altitude conversion chart for negative pressure gauges. In order to achieve 15 kPa absolute pressure, use the chart
on the following page to determine your corrected 15 kPa value.
For greatest accuracy, use the lab barometer or check with the local weather bureau for current [or average]
barometric pressure in your location and reference that to the pressure indicated in the gray-shaded columns on the
table below.
Prentex assumes no responsibility to determining the proper ambient barometric pressure for your specific location.

Operator’s Manual for Prentex Model 9900E Vacuum Degassing Oven
Page -4-
Altitude
[feet]
Standard Atmosphere 15kPa Altitude
[feet]
Standard Atmosphere 15kPa
inches
Hg
mm
Hg kPa
in Hg
corrected
inches
Hg
mm
Hg kPa
in Hg
corrected
029.92 760.00 101.3 -25.49 ± 0.74 4,000 25.84 656.34 87.5 -21.41 ± 0.74
500 29.39 746.51 99.5 -24.96 ± 0.74 4,500 25.36 644.14 85.9 -20.93 ± 0.74
1,000 28.86 733.04 97.7 -24.43 ± 0.74 5,000 24.89 632.21 84.3 -20.46 ± 0.74
1,500 28.34 719.84 96.0 -23.91 ± 0.74 5,500 24.43 620.52 82.7 -20.00 ± 0.74
2,000 27.82 706.63 94.2 -23.39 ± 0.74 6,000 23.98 609.09 81.2 -19.55 ± 0.74
2,500 27.32 693.93 92.5 -22.89 ± 0.74 6,500 23.53 597.66 79.7 -19.10 ± 0.74
3,000 26.82 681.23 90.8 -22.39 ± 0.74 7,000 23.09 586.49 78.2 -18.66 ± 0.74
3,500 26.33 668.78 89.1 -21.90 ± 0.74
3.8 Using the Altitude / barometric pressure conversion chart. Once you have determined the corrected value [in/Hg]
for your location, rotate the gauge to align that gauge value with the 15kPa line on the absolute vacuum scale
printed on the 9900 surrounding the gauge.
Example: If your local barometric pressure is 26.33 in/Hg, the 15kPa equivalent reading [in/Hg] is -21.90 ± 0.74 in/Hg.
Therefore, setting the gauge’s -22 opposite the outer scale 15kPa mark will provide approximately the correct
adjustment for your barometric pressure.
3.9 Prentex Model 9900 Vacuum Ovens starting with serial number 93017 are provided with an adjustable gauge mount
that permits aligning the correct negative gauge pressure with the kPa scale printed on the cabinet.
Note: The gauge’s orientation is restrained by a friction drag mechanism and may be very stiff to rotate.
3.10 Adjusting the Vacuum System to 15 kPa ±2.5 kPa. Completely close the manual bleed valve located on the cover
[clockwise]. Start the Vacuum Oven. Once preheating is complete and “Ready” is displayed, press the “Start
Process” button. After the vacuum pressure has stabilized, adjust the manual bleed valve until the vacuum is at 15
kPa [or within 15 kPa ±2.5 kPa].

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Operator’s Manual for Prentex Model 9900E Vacuum Degassing Oven
Page -5-
4.0 Operating the Prentex Model 9900 Vacuum Oven
Notes:
[1] The Model 9900 Vacuum Oven is specifically designed for the purpose of degassing PAV-aged asphalt binder samples.
Although the Vacuum Oven may be suited to other applications, such use may void the manufacturer’s warranty.
[2] In order to maintain proper sample depth, it may be necessary to use smaller sample tins than the ones supplied.
[3] In the case of asphalts that tend to foam aggressively, keeping the sample depth to the minimum allowed is highly
recommended.
[1] Turn on power. Display indicates idLE . . . XXX
[XXX is the actual temperature in vacuum chamber.]
[2] At least one hour before you will need to degas a sample, press the Preheat Button. System displays HEAT . . . to . . .
170 . . . . . . XXX.
[3] When chamber reaches 170, display changes to rEAdY . . . 170 and audible alarm sounds - load sample.
Note A: If the sample has not been loaded and the temperature reaches 175, rEAdY will disappear, and the system will
revert to HEAt . . . to . . . 170 . . . . . . XXX while it cools. When it cools to 174, the rEADY should reappear. The
temperature should stabilize at approximately 170 ±2, then load samples.
Note B:
IF rEAdY has not come back on, remove the cover, load the samples and fan some room-temperature air on the
temperature sensor. When it cools to 174, display will return to rEAdY and the audible alarm will again sound. At this
time, place the cover back on the Vacuum Oven and press the Start Process Button. System displays 10:00 . . .165. . .
. 9:52 . . . 166 . . . and continues to count down while cooling or reheating for 10:00 minutes. At 00:30, an alarm will
sound briefly, followed at 00:00 by the vacuum system switching on; the system will display 30:00 . . .170 . . . . .29:52 . .
.170 . . . , while applying vacuum and maintaining heat for 30:00 minutes. At end of 30:00 minutes, the system will
release vacuum and shut off power to the heaters and will sound an audible alarm. The display will return to idLE. . ..
Note:
Some asphalts will tend to foam aggressively even when sample depth is kept to the minimum allowed.
It is advisable to check for excessive foaming during the first portion of the degassing process. In some cases, it may
be necessary to stop and restart the vacuum more than once.
[4] Start process by pressing ‘START PROCESS’ button. There will be a 10:00 minute reheat as the system replaces the
heat lost from inserting the samples. At 00:30 on the countdown, an audible alarm will sound. At 00:00 the vacuum
system will switch on.
The Display will begin countdown from 30:00 while processing samles. Heat and vacuum will maintain for the duration.
At the end of the process (30 minutes) the system (VDO) will release vacuum and shut off power to the heaters. An
audible alarm will sound and display will return to ‘iDLE’.
[5] Remove sample promptly - CAUTION! - Vacuum chamber is HOT!
Stopping and Restarting Vacuum
To stop and restart vacuum, press the Stop ! ! button; when excessive foaming has subsided, press and hold the Start
Process button for 1 second; timing and vacuum pumping will restart at 30:00.
15:00
15:00
9:45

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Operator’s Manual for Prentex Model 9900E Vacuum Degassing Oven
Page -6-
5. Changing the Preset Values – Temperature, Time 1, Time 2
Although only three buttons are indicated on the controller front panel, six actually exist. Each has an LED directly above it
which may be identified by the small clear dot in the black front panel overlay. The diagram below shows this layout and
designates each button by number.
5.1 To change pre-programmed values, press and hold buttons 3
& 5 [“Start Process” and “Stop”] until display changes. At
this time, buttons 3 and 6 become “up” and “down” arrow keys,
respectively
5.2 Use arrows to DISPLAY:
“Temp” [Setpoint] ,
“Tine 1" [Time 1 = heat but no vac.] , or “Tine 2" [Time 2 = Heat
w/ vac.]
5.3 Once the value you wish to change is displayed, press button 1
to select that value and then use “Up” or “Down” arrows to
change it.
5.4 Confirm the change by pressing button 2. Now, you are back to 5.2 and may repeat the process by selecting another
value to change.
5.5 To exit the change menus, press button 2 twice.
6. Calibration of the Temperature Sensor
6.1 This process will work with either a digital calibrated temperature reference or a standard mercury thermometer [partial
immersion].
6.2 Fill a 250 ml [4 oz] tin with a minimum of 37 mm [1.5"] of light oil [motor oil, silicone oil or mineral oil are suitable]. Place
it in one of the sample recesses in the sample support plate in the bottom of the oven, and preheat the oven.
6.3 For users of digital probes with flexible leads, make a clip that will support the probe in the tin of oil, submerged but not
in contact with the bottom or sides. Cover the vessel, letting the lead-wire come out under the lid. Allow the temperature
to re-stabilize. Record both the 9900's indicated temperature and the reference standard’s indicated temperature.
1
Select
4 6 5
2
Confirm
/ Exit
3
ø
ø ø
ø
This process will work with a digital calibrated temperature reference.
Attach the thermo probe to the calibration block by threading thermo probe through center hole in block. Insert
calibration block into center space in sample rack. Ensure there is contact of the thermo probe to the sample
rack after placing calibration block.
Replace the lid to the unit (the wire to the thermo probe will prevent the lid from attaining complete closure).
Press the Preheat button on the front of the unit and wait for the temperature to increase and stabilize for at
least one hour. Record the indicated temperature and the reference standard’s indicated temperature.
6.2
6.3

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Operator’s Manual for Prentex Model 9900E Vacuum Degassing Oven
Page -7-
6.4 For users of glass thermometers and rigid digital probes, remove the calibration plug from the lid [or remove the
metering valve if the oven has one]. Locate the calibration hole over the oil-filled tin and use a clip to suspend the
thermometer in the oil with its immersion line even with the bottom of the lid. Suspend rigid digital probes so that the tip
is well-immersed [at least 1"] in the oil. Allow the temperature to stabilize for a minimum of one hour. Record both the
9900's indicated temperature and the reference standard’s indicated temperature.
6.5 Adjusting the Calibration Offset in the Model 9900's controller: If there is a difference between the indicated temperature
on the Model 9900's display and that of the calibrated reference thermometer or digital probe, an offset is user-
accessible to get the 9900 back to a true reading. Please refer to the drawing in Section 6 of your Operator’s Manual for
a guide to the buttons on the 9900's front panel.
6.6 Although only three buttons are indicated on the controller front panel, six actually exist. Each has an LED directly
above it which may be identified by the small clear dot in the black front panel overlay. The diagram in Section 6 shows
this layout and designates each button by number.
6.7 To change the calibration offset value, press and hold buttons 3 & 6 [“Start Process” and the one below it] until the
display changes. Buttons 3 and 6 will now become “up” and “down” arrow keys, respectively. If the display does not
read “SetUP”, use either button 3 or 6 to reach “SetUP”.
6.8 Now Press Button 1 [‘Preheat”] to select the Setup Menu. Then, press Button 6 to display “OFFSt1”. Again press
Button 1 to select “OFFSt1” as the parameter to be changed.
6.9 If the Model 9900's displayed temperature was below the reference standard’s indicated temperature, you will use
Button 3 to increase the calibration offset. If the 9900's displayed temperature was above the reference standard’s
indicated temperature, use Button 6 to decrease the calibration offset. Increase or decrease the displayed Offset value
from its current reading by the number of degrees low or high that the 9900's display indicated.
6.10 Press button 2 repeatedly to confirm the Offset 1 value and return to the 9900's normal display.
Remember to remove the calibration block and thermo probe at the end of the calibration process.

Operator’s Manual for Prentex Model 9900E Vacuum Degassing Oven
Page -8-
6.11 Compare the new indicated temperature on the 9900 with the temperature indicated by the reference standard. If within
1 degree, observe the temperatures for at least 5 minutes. Since the 9900 can only be calibrated in 1-degree
increments, and its readings may change in between the “exact” degree increments on the reference standard, it may
not be possible to achieve an offset that will allow the 9900 to agree with the reference standard at all times, but it should
be possible to keep the two within 1 degree. If necessary, repeat steps [7] through [11].
7 Calibrating The Vacuum Gauge
7.1 Remove the calibration plug from the lid, or remove the metering valve if the oven has one.
7.2 Install a calibrated [NIST-Traceable] vacuum gauge in the calibration port, using teflon pipe tape or vacuum grease to
seal the threads.
7.3 Place the lid on the vacuum vessel. Preheat the oven and press “Start Process”. Allow the vacuum system to actuate
and pressure to stabilize.
7.4 Compare the indicated reading on the Model 9900's gauge with the calibrated gauge. Note: due to the relatively small
gauge size on the Model 9900, it may be easier to get an accurate reading as the vacuum pressure is rising and exactly
on a marked interval on the 9900's gauge, such as 25.0 IN Hg. You might, for instance note: “At 25.0 indicated, actual
vacuum is 25.2 In Hg”, as opposed to trying to determine whether the 9900's gauge is indicating 25.2 or 25.3 when the
calibrated gauge is at 25.4. Note any error and post the offset on the Model 9900's front panel for reference. Wording
similar to “At an actual vacuum reading of 25.5, the gauge will indicate 25.3" will be helpful in daily use of he equipment.