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May 1990

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Document:	VAXft Systems Addendum
Order Number:	EK-VXFT1-AD
Revision:	001
Pages:	19
Original Filename:

OCR Text

VAXft 3000 Site Preparation and
Installation Guide Addendum
Order Number EK-VXFT1-AD

digital equipment corporation
maynard, massachusetts

May, 1990
The information in this document is subject to change without notice and should not
be construed as a commitment by Digital Equipment Corporation. Digital Equipment
Corporation assumes no responsibility for any errors that may appear in this document.
The software described in this document is furnished under a license and may be used or
copied only in accordance with the terms of such license.
No responsibility is assumed for the use or reliability of software on equipment that is not
supplied by Digital Equipment Corporation or its affiliated companies.
Restricted Rights: Use, duplication, or disclosure by the U. S. Government is subject to
restrictions as set forth in subparagraph ( c ) ( 1 ) ( ii ) of the Rights in Technical Data and
Computer Software clause at DFARS 252.227–7013.
Copyright © Digital Equipment Corporation 1990
All Rights Reserved.
Printed in U.S.A.

CompacTape
CompacTape II
DEC
DEC/CMS
DEC/MMS
DECmate
DECsystem
DECUS
DEC WANcontroller 620

DECwriter
DIBOL
DSSI
MASSBUS
MicroVAX
PDP
P/OS
Professional
Rainbow
RSTS
RSX

RT
ThinWire
TK
ULTRIX
UNIBUS
VAX
VAXcluster
VAXft
VMS
VT
Work Processor

This document was prepared and published by Educational Services Development and
Publishing, Digital Equipment Corporation.

Contents
1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
Design Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1
Unit Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2
Unit Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3
Center of Gravity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.4
Rack Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.5
Heat and Airflow Management . . . . . . . . . . . . . . . . . . . . .
2.5.1
Internal BTUs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.5.2
Air Vents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.6
Data Cable Management . . . . . . . . . . . . . . . . . . . . . . . . . .
2.7
Grounding Considerations . . . . . . . . . . . . . . . . . . . . . . . . .
2.8
Power Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1
2
2
3
3
10
11
12
12
12
14
14
15

Figures
1
2
3
4
5
6
7
8

BA22A Box — Front View . . . . . . . . . . . . . . . . . . . . . . . . . . .
BA22B Box — Front View . . . . . . . . . . . . . . . . . . . . . . . . . . .
Flange Mounting Holes . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BA22 Box — Side View . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rackmount Example — Front View . . . . . . . . . . . . . . . . . . . .
Typical VAXft 3000 Rack Mounted — Side View . . . . . . . . . .
Traditional Rackmounted Equipment — Side View . . . . . . . .
Cable Routing Example — Front View . . . . . . . . . . . . . . . . . .

4
5
6
7
8
9
10
13

iii

1 Introduction
This is a preliminary procedure for OEM customers to mount VAXft 3000
BA22 boxes into custom 19-inch cabinets.
This document is meant to be used with the VAXft 3000 Site Preparation
and Installation Guide (EK-VXFT1-IN).
The VAXft 3000 system is offered in two basic mounting styles: office
pedestal and OEM rackmount. The processor and mass storage expanders
are contained in BA22-style equipment boxes.
The office pedestal is designed to operate in office or computer room
environments, and has the following features:
•

Enclosure skins and covers

•

Split-entry front door

•

Base mounted on casters

The OEM rackmount box version differs from the office pedestal version
in that it has:
•

No skins or covers

•

A rackmount base instead of the office base

The rackmount base ensures support for the transformer and allows
spacing for required airflow.
The purpose of the rackmount base is to provide:
•

Separate air paths between the units

•

A mounting support for a lifting device, such as a forklift

The rackmount option consists of:
Attached rackmount assembly
Front cover
Instructions

2 VAXFT 3000 Site Preparation and Installation Guide Addendum

2 Design Concerns
The design concerns for rack mounting a VAXft 3000 system into a custom
rack or cabinet are:
•

Unit weight

•

Center of gravity

•

Unit dimensions

•

Rack construction

•

Rail mounting system

•

Heat and air flow management

•

Data cable management

•

Grounding considerations

•

Power distribution

2.1 Unit Weight
A major design concern for rack mounting the VAXft 3000 system is unit
weight. Each VAXft 3000 BA22 box can weigh up to approximately 108
kg (240 lb) for the processor box and up to 122 kg (270 lb) for the mass
storage expander box. Therefore, the cabinet’s 19-inch Radio-ElectronicsTelevision Manufacturers Association (RETMA) rail system must be
designed to handle a hang weight of 231 kg (510 lb) (one BA22 processor
and one BA22 expander box mounted on a one rail system) plus a safety
margin. It is recommended that the final rail assembly with two BA22
boxes be designed to withstand a 10 gravity peak, 10-ms shock pulse in
the vertical plane.
A second concern while handling the BA22 boxes is safety. When rack
mounting the BA22 boxes into the cabinet, it is recommended that a
lifting device be used. The suggested lifting device is a flat-blade fork-lift.
CAUTION
The BA22 boxes must be picked-up from the bottom. Never use
any sort of hook or try to lift the unit by its sheet metal skins.

VAXFT 3000 Site Preparation and Installation Guide Addendum 3

2.2 Unit Dimensions
The VAXft 3000 BA22 boxes are designed to be mounted into 19-inch
RETMA rail cabinets. If your cabinet does not have a 19-inch RETMA
rail system, then you have to design a conversion bracket. For example,
many phone company racks are based on a 1-inch center hole pattern, so
conversion brackets have to be custom made.
The dimensions for the rackmount VAXft 3000 BA22 boxes are:
•

60.96 cm (24.0 in) height of main box

•

66.14 cm (26.04 in) height of main box plus rackmount base

•

44.55 cm (17.54 in) width of main box (inside of rails)

•

46.78 cm (18.42 in) width of main box (flange to flange)

•

29.90 cm (11.77 in) depth plus 10.16 cm (4.0 in) for the rackmount
base extension in the rear

See Figures 1 and 2 for front views. See Figure 3 for the rail hole pattern.
See Figure 4 for a side view.

2.3 Center of Gravity
As seen in Figures 1 and 2, the BA22 boxes are 29.90 cm (11.77 in) deep.
This means that much of the center of gravity is toward the front rail
system. If your cabinet is, for example, 121.9 cm (48.0 in) deep, the
center of gravity is in the front quarter of the cabinet, causing a possible
tip hazard. If you use a cabinet that is 76.2 cm (30.0 in) wide by 152.4
cm (60.0 in) high by 66.14 cm (26.04 in) deep, the center of gravity is
acceptable approximately 35.56 cm (14.0 in) from the front of the cabinet.
See Figure 5 and Figure 6.
If deep cabinets (for example, 121.9 cm (48.0 in)) are used, and if no
equipment is going to be mounted on the cabinet’s rear rails to counter
balance the front load of the BA22 boxes, then an anti-tip front foot plate
must be used, if the cabinet is mounted on casters. If the cabinet is bolted
to the floor, then such an anti-tip plate can be omitted. In either case, the
shipping skid must be designed to handle the cabinet’s center of gravity
correctly and not accidentally tip while being moved.

4 VAXFT 3000 Site Preparation and Installation Guide Addendum

44.55 cm
(17.54 in)

TOP VIEW

29.89 cm
(11.77 in)

46.78 cm
(18.42 in)
46.51 cm
(18.31 in)
STANDARD 19-INCH RACKMOUNT
EIA MOUNTING HOLES
CENTER TO CENTER
MOUNTING
FLANGE

66.14 cm
(26.04 in)

5.08 cm
(2.0 in)

RACKMOUNT
BASE

44.55 cm
(17.54 in)
MR_0539_90.DG

Figure 1

BA22A Box — Front View

VAXFT 3000 Site Preparation and Installation Guide Addendum 5

44.55 cm
(17.54 in)

TOP
VIEW

29.90 cm
(11.77 in)

46.79 cm
(18.42 in)

46.51 cm
(18.31 in)
EIA MOUNTING HOLES CENTER TO CENTER

X
5

60.96 cm
( 24.0 in)

5.08 cm
( 2.0 in)
RACKMOUNT
BASE
FRONT VIEW
EXPANDER BOX
MR−0544−90.RAGS

Figure 2

BA22B Box — Front View

6 VAXFT 3000 Site Preparation and Installation Guide Addendum

MOUNTING FLANGE

TOP
46.51 cm
(18.31 in)
EIA MOUNTING HOLES CENTER TO CENTER

3.33 cm
(1.31 in)
TAPE OR
DISK

8.89 cm
(3.50 in)

21.91 cm
(8.63 in)
40.96 cm
(16.13 in)
DC BOX

49.85 cm
(19.63 in)

60.96 cm
(24.00 in)

5.08 cm
( 2.00 in)

AC BOX

SUPPORT
BRACKET

BOTTOM

RACKMOUNT BASE

FLANGE MOUNTING HOLES

2.86 cm
(1.12 in)
MAX
MR−0546−90.RAGS

Figure 3

Flange Mounting Holes

VAXFT 3000 Site Preparation and Installation Guide Addendum 7

10.16 cm
(4.0 in)

30.12 cm
(11.86 in)

66.14 cm
(26.04 in)

FRONT

REAR

RACKMOUNT BASE

5.08 cm
(2.0 in)

SIDE VIEW
MR−0545−90.RAGS

Figure 4

BA22 Box — Side View

8 VAXFT 3000 Site Preparation and Installation Guide Addendum

70-24742-02 FRAME
46.51 cm
(18.31 in)

CABLE
AREA

CABLE
TO
RIGHT

HOLE 54
.64 cm
(.25 in)
152.4 cm
(60.0 in) MUST SIT ON
MOUNTING
ANGLE BRACKETS
SHELF CAN BE
AN L BRACKET
TO REAR RAILS.

REQUIRED
MINIMUM SPACE
FOR AIR
CIRCULATION

CABLE
TO
RIGHT

HOLE 9
BASE COVER
(AIR PLENUM)

MR_0542_90.DG

Figure 5

Rackmount Example — Front View

VAXFT 3000 Site Preparation and Installation Guide Addendum 9

TOP

FRONT RAIL

VAXft 3000
BA22 BOX

RACKMOUNT BASE
OEM DESIGNED
SUPPORT
ANGLE BRACKETS

FRONT

REAR

INDENT FRONT RAILS
SO THAT DOOR CAN
OPERATE
(IF THERE IS A
FRONT RACK DOOR).

REAR RAIL

BOTTOM
PLACE CENTER OF
GRAVITY NEAR CABINET
CENTER OF GRAVITY.
MR_0541_90.DG

Figure 6

Typical VAXft 3000 Rack Mounted — Side View

10 VAXFT 3000 Site Preparation and Installation Guide Addendum

2.4 Rack Construction
Many 19-inch RETMA rail racks are not designed to support a heavy
weight on the front rail system alone. Such racks are designed to
hold front to back equipment boxes where the box weight is distributed
between the front and rear rails. See Figure 7. This distribution makes
sure that the cabinet does not flex.
The VAXft 3000 BA22 boxes are designed to be mounted on the front and
rear rail system. See Figures 4, 6, and 7. The front flanges are designed
for a RETMA hole pattern. The unit sits on an integral rackmount
base assembly that extends 10.16 cm (4.0 in) beyond the rear of the box
(see Figure 4). The BA22 boxes must then be supported by a customerdesigned right angle bracket that connects to both the front and rear
mounting rack rails (see Figure 6).
CAUTION
Never mount the BA22 boxes by the front mounting flanges only.
Always include supporting angle brackets so that the weight can
be distributed to the rear rail system. The front mounting flanges
can be damaged without the use of the angle brackets.
TOP

REAR RAIL

FRONT RAIL

SLIDES

REAR

FRONT

TYPICAL 48.26 cm (19.0 in)
RACKMOUNT FOR
CONVENTIONAL BOX-MOUNTED
EQUIPMENT ON SLIDES.

BOTTOM

Figure 7

MR_0540_90.DG

Traditional Rackmounted Equipment — Side View

VAXFT 3000 Site Preparation and Installation Guide Addendum 11

2.5 Heat and Airflow Management
The maximum power for each BA22 box is 750 Watts, or 2557 BTUs. It is
recommended that the cabinet be designed for the maximum configuration
per the user’s environment (temperature, humidity).
The tested operating ranges for the VAXft 3000 system are:
10°C to 40°C
50°F to 104°F
10% to 90% RH noncondensing
28°C (82°F) maximum wet-bulb temperature
2°C (36°F) minimum dew-point temperature
It is recommended that the rack environment be near the middle of the
tested operating ranges. This would be in the area of 40% to 60% RH,
18.3°C (65°F) to 23.8°C (75°F).
The rackmount version of the VAXft 3000 BA22 boxes comes with a
rackmount base. The base adds 5.08 cm (2.0 in) to the overall height of
the unit and 10.16 cm (4.0 in) to the overall depth (see Figures 1 through
4). The rackmount base adds the 10.16 cm (4.0 in) so that air can be
baffled correctly. If the rack has enough free airspace surrounding the
BA22 boxes, a flushing fan is not needed inside the rack. Initial tests
of two boxes mounted in a one and one-half bay cabinet with dimensions
of 152.4 cm (60.0 in) height, 76.2 cm (30.0 in) width and 66.04 cm (26.0
in) depth, showed that a flushing fan is not needed provided that the
ambient temperature is held below 40°C (104°F). If the rack has smaller
dimensions, some sort of blower, heat exchanger, or active cooling (air
conditioner) need to be considered.
The cabinet rackmount and airflow design depends on the following
factors:
•

Internal BTUs generated in the cabinet

•

Temperature differential between the inside cabinet temperature and
outside cabinet temperature

•

Surface area of all the outside walls of the cabinet

•

Whether cabinet rack walls are insulated or not insulated

•

Mounting configuration of the BA22 boxes within the cabinet

•

Airspace within the cabinet

•

Air vents on the front and rear doors or panels

If a flushing fan is used, note that the BA22 airflow is from top to bottom.

12 VAXFT 3000 Site Preparation and Installation Guide Addendum

2.5.1 Internal BTUs
The internal BTUs generated by a dual zone VAXft 3000 system mounted
in a single cabinet would be a maximum of 750 Watts 2 zones 3.41
equals 5115 BTUs. A 20 percent safety factor should be added to this.

Therefore, a maximum system cabinet should be designed to remove
6138 BTUs worth of heat (one cabinet with two processor cabinets or one
cabinet with a processor and expander cabinet).
2.5.2 Air Vents
The air intake slots in the front rack door should be a minimum of 225.82
cm (35.0 sq in) to allow for adequate intake airflow. The same is true for
the rear cabinet exhaust panel or door.

2.6 Data Cable Management
All cables connect to the VAXft 3000 BA22 boxes by means of the front
module panels, DSSI cable bulkheads, and console bulkheads. This means
all cable routing must be addressed from the front of the units.
Figure 8 shows the recommended cable dressing.
If the BA22 boxes are mounted in a 152.4 cm (60.0 in) high rack, there
is no room between the BA22 boxes for the routing of cables. All I/O
cables must be routed to the right or left sides. Cross-link cables must be
mounted vertically.
If the BA22 boxes are mounted in a 165.1 cm (65.0 in) or higher rack,
cables may be routed between the BA22 boxes.

VAXFT 3000 Site Preparation and Installation Guide Addendum 13

FRONT VIEW

IF CABINET IS
165.1 cm (65.0 in)
OR TALLER,
CABLE UP/DOWN.

BASE COVER
(AIR PLENUM)

LEAVE OPENING
BETWEEN UNITS
FOR CABLING.

BASE COVER
(AIR PLENUM)

MR_0543_90.DG

Figure 8

Cable Routing Example — Front View

14 VAXFT 3000 Site Preparation and Installation Guide Addendum

2.7 Grounding Considerations
It is very important to have a good common ground between the two BA22
boxes when mounted in a rack assembly. The following rules apply:
•

The mounting rails should be conductive so that there is a good
ground contact between the upper BA22 front mounting rails and the
bottom BA22 front mounting rails.

•

If the rails are to be painted, consult with Digital Equipment
Corporation.

•

The mounting rails should be connected to a cabinet ground.

•

In multiple cabinet systems, all cabinet grounds must be tied together.

2.8 Power Distribution
Each VAXft 3000 BA22 box has its own power cord. Each cord is rated
for a 12 A, 120 Vac outlet or 6 A, 240 Vac outlet maximum. These are
standard wall outlets.
The one major concern when adding power controllers to a cabinet or rack
is that a single point of failure should be avoided. For example, it would
be easy to add a 30 A, 120 Vac rated power controller to the cabinet for
120 Vac systems, and plug both BA22 boxes into the one power controller.
This is fine, but by doing this, a single point of failure is introduced — the
power controller. If the relays or EMI/RFI filter fail, both BA22 boxes go
down.

VAXFT 3000 Site Preparation and Installation Guide Addendum 15

3 Summary
In summary, the OEM designer should use the following guidelines when
designing a 19-inch cabinet rack for VAXft 3000 systems:
•

Use the rackmount version of the VAXft 3000 system. Do not try to
convert an office version, since the office version is not supplied with
the appropriate rackmount base.

•

Two BA22 boxes weigh up to 108 kg (240 lb) for the processor BA22
plus 122 kg (270 lb) for the expander BA22 for a total of 231 kg (510
lb). The cabinet and rail system must be designed to support this
weight plus a safety margin. Both the front and rear rails must be
used to distribute the weight. A custom mounting shelf or angle
brackets must be designed by the OEM customer to do this.

•

The BA22 boxes are shallow (29.89 cm or 11.77 in). Special
consideration must be made about the cabinet’s center of gravity,
especially during transportation.

•

The maximum heat generated by a single BA22 box is 2557 BTUs.
A single 60 inch cabinet could be designed to hold two BA22 boxes,
therefore generating 5115 BTUs. It is suggested that a 20 percent
safety factor be added to this resulting in a 6138 BTU design center,
maximum.

•

A minimum of 225.82 sq cm (35.0 sq in) must be allowed for air intake
vent open area (total slot size open area). The same is true for the
exhaust area.

•

If the air temperature outside of the cabinet is expected to be above
the range of 18.3°C to 23.8°C (65°F to 75°F), active cooling such as
industrial cabinet air conditioners should be investigated.

•

Airflow in the BA22 boxes is from top to bottom. If cabinet flushing
fans are needed as a result of airflow studies, the flushing fans should
not work against the BA22 airflow.

•

The use of a single power controller for two BA22s within the same
19-inch cabinet can introduce a single point of failure.

•

Grounding is very important. Use conductive mounting rails.