PS Magazine - MAY 1972
PS, The Preventative Maintenance Monthly
1972 SERIES, ISSUE 234
MAY 1972
MATCHED FILTER
-±
,
eleMeNTS
I
Both filter eLements in
your M±7 or M²7A± mask
must show tHe same lot
number. If the numbers
don't match, or they're not
readable, the elemeOCs are
unserviceable.
The
serV-
³ceable fiLter eLement Lots
are listed ³n SB 3´30µ2 (Nov
70)
.
.±²,;³´:µ¶
¶edium and the large
·17´series masks use a medium
faceblank¸ ¹he larGe mask, however,
is equipped with a large nosecup,
it has an
L
stamped alongside
COMPONEnT SIZE
Molded S o± facebla±k
a±d molDed or stamped
M o± ±osecup
MolDeD M o± facebla±k
a±d molded or stamped
M o± ±osecup
²olded ² with a stamped
l
alo³gside it, o± tHe
facebla±k, a±D a molD
e
d
or stampeD Lo± the ±ose
-
cup
¹o open your·17 or·17A± mask
carrier, always pull out on the center
of the flap. ¹he flap fasteners will
give easyºlike» If you pull on the
corners of the flap, your lopsided
yank'll strip off the flap eyelets,
sending your carrier Co support for
new eyelets.
.±²³T-;
¼He ¶olded · on the faceblank¸ ¹He
´
s¶all ¶ask uses a medium nosecup¸
J
\
When all markinGs are in Good
I
order, mask sizing stacks up Like
I
this:
MASK SIzE
S (small)
M
(
medium)
l
(larGe)
FSn
4240´54µ´4450 (M¶7)
4240´926´4199 (M¶7A·)
424
0
¸
¹42¸44¹1 (M·7)
4240´926
´
4201 (M¶7A¶)
4240
´
542
¸
44¹2 (²¶7
)
4240¸926¸4200 ( M º7 A¶»
i
-
·
'
GO EASY ON THe STAMPeD MARKINGS
59
If tHe sCamped sizing
info's worn
off or washed off you maY end up with
a sizinG puzzle¸ So go easy on the
stamped ¶arkings when you handle or
clean the mask½
If some, or all, of the markinGs are
missing, Here¾s a sizing guide that¿ll
HeLp:
¼f ½¾ere
'
s a molded S o± the face¿
bla±k a±À ±o Áark o± the ±osecup, you
ca± be fairly sure that you have a small
mask
.
¼f yoU have a ÁolDed M o± the face
Â
bla±k a±d ±o siÃe o± the ±osecupÄ co±Å
siDer the sÆÃe u±k±ow³Ç (The stamped
l
o± the facebla±k may have wor± oÈÈ
ÉÇÇ
a±D WÆthout a siÃe o± the ±os
e
cup
,
youÊll
±ot k±oW for sure w¾ether you have a³
M or a±
l
maskÇ) I± this ki±d of pi±ch
YoU ca± ½rY ½he fitti±G a±d leakaGe test
SOP i± the maskËs TMÌ to see if the
Áask
Ë
ll fit a±d work for You
Ç
Or
Ì
you ca±
tUr± the mask i± for o±e thatËs properly
ÁarkeD
Í
If yoU have a molded M With a± L
s
½ampeD alo±GsiDe it o± tHe facebla±Î,
a±D ±o mark o± the ±osecupÏ you ca± be
fairly sUre you ¾ave a larGe mask
Ç
For fi½½
i±
GÌ PM
Ì
a±D sUpply scoop o±
½he M¶7A¶ you ±eeD TM 3
¸
4240
´
258Ð14
(
Mar 7Ñ) a±D its
¸
20P TM
(
Mar 68)Ç The
M¶7 Áask is covereD by TM 3¸4240
¸
2Ò2¸14 (JUl 7º) a±D its compa±io± ¸20P
(Jul 68)Ç
Never Use pai±t, maGÆc Áarkers or
a±y kƱÀ of Ʊk to sÆÃe or ÆDe±tify your
Áask
Ç
Same Goes for its carrier
Ó
Ôou ca±
Use tra±spare±t tape for marki±G the
carrier a±D a taG coDe, of some ki±d, to
ÆDe±tifY your Áask
Õ
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