UFC 3-280-03
23 JULY 2003
complexity of the system, and the capability of personnel required to run the system. In
general, manual control (i.e., manual valves or local push-button controls) would be
appropriate for small installations and presses that do not require additional systems
such as conditioning. Typically, industrial processes fit this category while wastewater
sludge treatment rarely fits. For wastewater applications, control systems generally fall
into one of three categories: remote manual, semiautomatic, and fully automatic.
2-4.7.1.1 Remote Manual Systems. These typically work as follows:
All system functions are controlled by an operator from a centrally located
panel.
All operating elements, such as valves and pumps in the filter press and
associated support systems, are individually opened, closed, started, and
stopped by manipulation of switches located at the central control panel.
The control panel for this remote system typically includes operating switches
for each element and indicator lights showing their status, an alarm telling when the
filter cycle is complete, and an indicator and an annunciator to sound an alarm under
specific conditions. This panel may also be equipped with color coded interconnecting
lines with arrows to guide the operator in the proper sequence of actions to be taken.
In addition to the features described above, the remote manual system is also
equipped with features such as safety light curtains and interlocks that cause the
system to automatically stop if specific conditions are not met. Detailed descriptions of
the safety light curtain and interlocking systems are presented in Subparagraph 2-
4.7.2.3.
2-4.7.1.2 Semiautomatic Systems. A semiautomatic control system typically consists
of subcycles within the dewatering process that can be manually started or stopped,
such as the prefill and precoat, start filtration or feed, core blowing, sludge cake
discharge, and filter media wash cycles. This control system consists of an alarm that is
given at the end of each subcycle to alert the operator that the next subcycle can be
initiated. This type of system will normally include a graphic representation of the
system with status indicators for all operating components.
This type of system typically contains one central control panel and
distributed local control panels, or subpanels within the central panel to control the
subcycles. The control of the subcycle is typically initiated by an automatic switch
located on or within the local panel or subpanel. As with the remote manual system,
safety and interlocking features are also provided. In addition to interfacing of central
and local remote panels, control panels and controls should be interfaced and
coordinated with other remote control systems, as required, such as a Supervisory
Control and Data Acquisition (SCADA) system, annunciators, etc., that may be used in
for monitoring process variables throughout the complete water or wastewater treatment
cycle.
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