©
Agilent Technologies 1989–2002
Agilent 3070 / 79000 Site Preparation
7-19
Chapter 7: Site Preparation – Compressed Air and Vacuum Requirements: Compressed Air and Vacuum Primer
Compressed Air
and Vacuum Primer
This section contains:
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Introduction
There are two key concepts involved in understanding
the compressed air and vacuum requirements for the
Agilent 3070 / 79000 system. The first is pressure and
the second is flow rate.
Pressure is the force per unit area that a gas exerts on a
surface. If zero is used as a reference, the measurement
of pressure is called “absolute”; if the local atmospheric
pressure is used as a reference, the measurement is
called “gage.” Although atmospheric pressure varies
with altitude and weather, gage pressure is typically
used for engineering measurements, so it is used in this
manual. A pressure value below zero gage is considered
a vacuum.
Common units for measuring pressure are kilopascals
(kPa), pounds per square inch (psi), and atmospheres
(atm).
Flow rate is the quantity of a gas moving through a
given area per unit of time. Since air is compressible,
you must know both the speed and pressure of the air
when measuring the flow rate. To reduce confusion, the
industry has agreed on a standard set of conditions for
flow rate measurements called “standard temperature
and pressure” (STP). The standard temperature is zero
degrees Celsius (32 degrees Fahrenheit), and the
standard pressure is one atmosphere (101.3 kPa or 14.7
psi).
Common units for measuring flow rate are liters per
second (l/s) and cubic feet per minute (CFM). When
using standard conditions, the units are written as “l/s at
STP” or “SCFM” (standard cubic feet per minute).
Compressed Air
The 3070 uses compressed air to activate both the
fixture pull-down towers and the vacuum valves. The
3070 also provides an outlet for supplying air to
accessory equipment such as handlers and air assisted
fixtures.
The minimum pressure needed is 480 kPa (70 psi). The
3070 has an internal regulator to restrict the maximum
pressure inside the system to 550 kPa (80 psi).
The flow rate needed is dependent on how often fixtures
are changed, but is generally much less than what is
available in most production areas. Additional air (flow
rate) may be needed to supply the outlet for custom
fixtures or presses depending on their requirements.
Vacuum
The 3070 doesn’t use any vacuum directly, rather the
vacuum is used by the fixture to pull a device under test
(DUT) onto the probes. The 3070 provides valves,
plumbing and control to assist in supplying vacuum to
the customer’s fixture.
