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Dental X-ray machine

A

Al A.

Jan 1, 1970
0
Anyone here know anything about dental X-Ray machines?
I have a few questions on a Phillips ORALIX 65 unit.

Any help would be much appreciated.
Thanks,
AL
 
T

Tom McEwan

Jan 1, 1970
0
Al A. said:
Anyone here know anything about dental X-Ray machines?
I have a few questions on a Phillips ORALIX 65 unit.

Any help would be much appreciated.
Thanks,
AL

I only know one thing about them - they're bloody dangerous! I really hope
you know what you're doing!

Tom
 
S

Sofie

Jan 1, 1970
0
Yea..... they are used by dentists who know what they are doing, know how to
properly operate the machine and know how to observe proper safety
procedures to take dental x-rays......
......... what else did you what to know?
 
A

Art

Jan 1, 1970
0
Suggest that you get the appropriate service information and are properly
trained before even attempting to enter the case. Otherwise have a factory
trained technician service it for you. Safety first, learn at your own
expense but not in a way to jeopardize your life. .
 
N

Norm Dresner

Jan 1, 1970
0
Al A. said:
Anyone here know anything about dental X-Ray machines?
I have a few questions on a Phillips ORALIX 65 unit.

Every X-Ray device I've ever seen uses very high voltages; 10-30KV is not
atypical.

There's a very fundamental High Voltage Service Rule:

Always keep one hand in your back pocket.

That way you can't unintentionally provide a direct path to ground from your
other hand.

Norm
 
J

Jules

Jan 1, 1970
0
Al A. said:
Anyone here know anything about dental X-Ray machines?
I have a few questions on a Phillips ORALIX 65 unit.

It's a 65kV (obviously!) machine, IIRC it has an 'oral technique' timer
which sets the exposure time according to oral position and film speed.
You won't get anywhere near the 65kV, unless you can get inside the head
unit which contains the tube and mains transformer. Check that any exposed
metal on the head is well grounded, for electrical (supply) safety.
 
A

Al A.

Jan 1, 1970
0
Yea..... they are used by dentists who know what they are doing, know how to
properly operate the machine and know how to observe proper safety
procedures to take dental x-rays......
........ what else did you what to know?
----------------

Yes, I know all of that.

As a matter of fact, I am working on this for a dentist who is going
to bring it to a village in a shockingly poor part of the world, in
order to provide dental care a few times a year to a place where the
last time there was any medical or dental care was nearly 7 years
ago. He does this strictly on donated money, and at great personal
risk and cost. I am trying to help him out. I have no intention of
taking any dental X rays, nor did I indicate any intent to do so.

I am converting this to be a portable unit (it was an "office mobile"
type, this is the third conversion I have done.) so that it can be
gotten there. Part of the trip is via canoe, and most of the rest is
via a beatup old 4WD truck, up some very treacherous mountain roads,
accompianied by armed guards. It will be run by generator.

I have been an electrical engineer for over 20 years. I design ,build
and service (12KV, 20KW) power supplies for electron beam vapor
deposition systems, and ion beam guns.

If you fear for my safety, I appreciate your concern, but please
don't. I have a mom and a wife for that.

I have several question concerning the type and amount of transformer
oil that is used in the head of one of these units. If anyone here
has, and is willing to offer, any specific knowledge about this unit,
I would much appreciate your assistance, it will be used to help
people who are truly in need.

If you have only to offer snide remarks like the one above, please
don't waste your time on me. I am not worth the effort, I assure you.

Thank you,
AL
 
A

Al A.

Jan 1, 1970
0
Suggest that you get the appropriate service information and are properly
trained before even attempting to enter the case. Otherwise have a factory
trained technician service it for you. Safety first, learn at your own
expense but not in a way to jeopardize your life. .


Thanks, Art. I do know enough to not get hurt, nor endanger anyone
else. (see my follow up posting to another reply I got)

I was just curious if there was anyone here who had some specific
knowledge about this unit. I was wondering as to how one determines
the correct oil level in the head of the unit. I think it is OK, as
the unit was working when it was taken out of service, but it is going
a long way from here, and I want to double check.

Thanks for the rational reply, it is much appreciated.
-AL
 
A

Al A.

Jan 1, 1970
0
Yea..... they are used by dentists who know what they are doing, know how to
properly operate the machine and know how to observe proper safety
procedures to take dental x-rays......
........ what else did you what to know?
----------------

Yes, I know all of that.

As a matter of fact, I am working on this for a dentist who is going
to bring it to a village in a shockingly poor part of the world, in
order to provide dental care a few times a year to a place where the
last time there was any medical or dental care was nearly 7 years
ago. He does this strictly on donated money, and at great personal
risk and cost. I am trying to help him out. I have no intention of
taking any dental X rays, nor did I indicate any intent to do so.

I am converting this to be a portable unit (it was an "office mobile"
type, this is the third conversion I have done.) so that it can be
gotten there. Part of the trip is via canoe, and most of the rest is
via a beatup old 4WD truck, up some very treacherous mountain roads,
accompianied by armed guards. It will be run by generator.

I have been an electrical engineer for over 20 years. I design ,build
and service (12KV, 20KW) power supplies for electron beam vapor
deposition systems, and ion beam guns.

If you fear for my safety, I appreciate your concern, but please
don't. I have a mom and a wife for that.

I have several question concerning the type and amount of transformer
oil that is used in the head of one of these units. If anyone here
has, and is willing to offer, any specific knowledge about this unit,
I would much appreciate your assistance, it will be used to help
people who are truly in need.

If you have only to offer snide remarks like the one above, please
don't waste your time on me. I am not worth the effort, I assure you.

Thank you,
AL
 
C

Ceraboy

Jan 1, 1970
0
Al A. said:
Anyone here know anything about dental X-Ray machines?
I have a few questions on a Phillips ORALIX 65 unit.

Any help would be much appreciated.
Thanks,
AL

The Phillips Oralix 65 has a 65kV, 7.5mA x-ray tube with a tungsten
target. X-ray tube is a "braking type" x-ray source with a variable
wavelength output. The voltage and current are fixed with a
20millisecond exposure and 0.7mm focal point. Line current is 9amps
at 120volts. Nominal radiation output is 500mR/sec (Rad = radiation
absorbed dose). Single exposure is 10millirads. Not a super
powerhouse when it comes to x-ray radiation sources, but can do damage
quick if you are not careful. 200,000 millirads will cause cataracts,
300,000 millirads will cause skin burns, 1,500,000 millirads will
cause severe burns, and 3,000,000 millirads will lead to skin grafts
and amputation. Dont make yourself a Darwin award winner if you have
no experience with x-ray sources. The oil cooled tubes on these
Oralix units are quite fragile, particularly the tungsten filament
cathode (electron source). Over time you will also fry the anode from
poor cooling and overuse(tungsten target). You can always replace the
x-ray tube, as they should be readily available.
 
S

sofie

Jan 1, 1970
0
Al A:
Sorry that I offended you with my "snide" remark.... it is an unfortunate
result of spending too many hours on newsgroups trying to determine how to
reply to the various types of requests for repair suggestions.
If you would have first posted the subsequent information that you did in
your follow up postings I would have offered more constructive comments and
suggestions, but the way that your original post was written made it seem
apparent to me that you were an inexperienced novice with a new "toy" that
you might have picked up at a garage sale or surplus sale.
On the newsgroups we get all kinds of crazy requests from newbies for help
fixing Microwave ovens, televisions, and other quite dangerous and deadly
home consumer devices that can otherwise be very safe is operated properly
and safety interlocks and covers are left in place. As I am certain that
you agree, these types of devices, including dental x-ray machines should
only be opened up and serviced by somewhat knowledgeable individuals.
Yes, your safety and the safety of others around you was my prime concern.
I trust that you will get the information you require for this worthwhile
endeavor with your dentist friend.
 
A

Al A.

Jan 1, 1970
0
Sir,
I appreciate your apology, it is big of you to offer it. You are
correct, I should have been a bit more specific and offered a bit more
info in my original posting. My error.

I guess I must also admit I may have been in a bit of a "mood" when I
replied. Hope that you took no offense, I really should not have
assumed you where being snide. If my reply came off as rude, please
accept my apology.

As someone who, like yourself, is called upon to defeat all of those
saftey interlocks and whatnot, just to do my job, I fully appreciate
the problem of being asked for advice from people who are not
qualified to saftely do the things they are asking about. Happens to
me all of the time. And I sometimes give advice similar to what you
gave me. I should have recognized it. I know well the issues involved
with newsgroup replies.

Thanks for taking the time to reply. No bad feelings I hope. BTW,
click the link below, and if you look closely, you can see one of my
other "converted" Xray machines in use in Papua New Guinea:

http://www.gracedentalmission.org/Missions-Galleries/Papua/PNG11.htm

I wa s modified to mount on a heavy duty camera tripod, and the whole
unit packs up into a fairly small suitcase type thing for transport.

hanks again,
-AL
 
E

Elton

Jan 1, 1970
0
Al A. said:
Anyone here know anything about dental X-Ray machines?
I have a few questions on a Phillips ORALIX 65 unit.

Any help would be much appreciated.
Thanks,
AL

Yes as soon as they are switched on your dental bill doubles!!

English joke, what do the call dentists in America?

answer Dennis
 
C

Ceraboy

Jan 1, 1970
0
Al A. said:
Yes, I know all of that.

As a matter of fact, I am working on this for a dentist who is going
to bring it to a village in a shockingly poor part of the world, in
order to provide dental care a few times a year to a place where the
last time there was any medical or dental care was nearly 7 years
ago. He does this strictly on donated money, and at great personal
risk and cost. I am trying to help him out. I have no intention of
taking any dental X rays, nor did I indicate any intent to do so.

I am converting this to be a portable unit (it was an "office mobile"
type, this is the third conversion I have done.) so that it can be
gotten there. Part of the trip is via canoe, and most of the rest is
via a beatup old 4WD truck, up some very treacherous mountain roads,
accompianied by armed guards. It will be run by generator.

I have been an electrical engineer for over 20 years. I design ,build
and service (12KV, 20KW) power supplies for electron beam vapor
deposition systems, and ion beam guns.

If you fear for my safety, I appreciate your concern, but please
don't. I have a mom and a wife for that.

I have several question concerning the type and amount of transformer
oil that is used in the head of one of these units. If anyone here
has, and is willing to offer, any specific knowledge about this unit,
I would much appreciate your assistance, it will be used to help
people who are truly in need.

If you have only to offer snide remarks like the one above, please
don't waste your time on me. I am not worth the effort, I assure you.

Thank you,
AL


Al,

The detials of your task are helpful. I have never directly worked on
this unit as I usually work with x-ray diffraction equipment which has
a water cooled jacket around the oil cooled tube for continuous
operation. Most new tubes that I am aware of are not serviceable (or
were not made to be serviceable), however, I have seen some tubes with
a plug that could be removed carefully to add oil. If the oil level
is low however, I would recommend replacing the x-ray tube all
together. Remember, less than 10% of the energy from the electron
source is converted to x-rays and remaining 90+% is dissipated as heat
which will eventually damage the anode target. If there is evidence
of oil loss, there is a good chance the tube may not last long in such
a remote location. The duty cycle on this unit is 50 seconds on, 10
minutes off. In my previous e-mail I said the exposure time was 20
milliseconds which is the minimum exposure, and I believe the unit is
adjustable to up to 2 second exposures. Depending on the previous
use, the tube could last or not. Also, I would be fairly concerned as
to the surviveability of this unit given such a rigorous trip as the
Oralix 65 & 70 were known to be more fragile than most. Good luck
 
S

Sam Goldwasser

Jan 1, 1970
0
FWIW, I think 10 percent efficiency is highly optimistic. Probably closer
to 1 percent for a typical X-ray source of this type. Of course, if
you have the actual specs, I'll defer to those. :)

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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Important: Anything sent to the email address in the message header is ignored.
To contact me, please use the feedback form on the S.E.R FAQ Web sites.
 
J

Jim Adney

Jan 1, 1970
0
I have several question concerning the type and amount of transformer
oil that is used in the head of one of these units.

I don't know anything about that unit specifically, but if you want
info on transformer oil I suggest you try to get the data sheets on
Shell Dialla and Dialla AX. I believe these are the 2 most commonly
marketed transformer oils in the US, and they are often used in
voltage ranges much higher than this.

In general, such transformers should not be completely filled (so that
there is air to act as something compressible when the oil gets warm
and expands), and the oil chamber should be sealed (so that moisture
can't get in.)

-
 
J

Jim Adney

Jan 1, 1970
0
Every X-Ray device I've ever seen uses very high voltages; 10-30KV is not
atypical.

A 30 keV X-ray is almost too weak to get out of the X-ray tube.
Medical X-ray machines run from 60 to 200 kV.
There's a very fundamental High Voltage Service Rule:

Always keep one hand in your back pocket.

I'm afraid that such a rule is really no help at all at truly high
voltages. At voltages like this you will still get nailed right thru
your shoes to a concrete floor.

The only safe way to work on them is by making SURE they are off and
completely discharged.

-
 
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