Interrupted pilots

In the case of an interrupted pilot, de-energize the safety shut-off valves. 

In general, burners can be ignited by a manual torch by a continuous, intermittent, or interrupted pilot burner or by direct electrical means per NFPA 86 (sect. 4-2.8.1 and sect. 4-3.8.1). Burners may also be ignited by autoignition due to a furnace temperature that is above the autoignition temperature per NFPA 86 (sect. 5-9 and sect. 5-17). See Section 10.4.9 for more details. 

Main burner flame establishing period (when ignited by interrupted pilot), sec 15 10 10... 

Figure 6.11 cites two potential hazards leading to explosions and fuel-fed fires from using constant pilots instead of interrupted pilots when a single flame monitor is used to check both pilot flame and main flame. (See pilot in the glossary.)... 

Fig. 6.11. Two time-line diagrams showing potential explosion situations. Use interrupted pilots-not constant pilots. (See glossary.) Courtesy of North American Mfg. Co.

When the motor overheats, the thermostat opens, interrupting motorline current. Pilot thermostats mounted on the windings of larger motors trip the motor starter rather than interrupt line current. This method gives good protection for sustained overloads, but because of the thermal time lag between the copper winding and the thermostat it may not provide adequate protec tion for stalled conditions or severe overloads. 

Two major questions regarding the applicability of this system remain to be discussed. First, how representative Is the catalyst sample In the mlnlreactor of the catalyst In the pilot plant And second, how does the Interruption of the reaction Influence kinetic behavior ... 

Many experiments were performed to answer the question of catalyst property changes due to repeated reaction Interruption. Every time the reaction Is stopped in the mlnlreactor to analyze the sample. It Is necessary to stop the reaction In the pilot plant as well to assure that the catalyst In pilot plant and mlnlreactor maintain Identical histories in reaction time. 

Tests should be conducted on the final packaged product. The protocol applied should be one that leads to minimal interruption of the standard manufacturing operations of the facility. Intermediate pilot plant studies should be carried out to simulate large-scale industrial sterilization cycles. The EtO cycle documentation should be integrated into a single protocol. An example of one protocol is as follows ... 

The constant OF2 yields obtained with current interruptions show we are approaching the consistent operation necessary for pilot plant synthesis or detailed mechanism studies. Our present study provides the necessary analysis, control techniques, and yield data and indicates areas for further possible improvements. However, achieving maximum yields will require study of more variables than we have surveyed here. 

Pilot, interrupted — A pilot that is ignited and bums during the light-off and is automatically shut off at the end of the trial-for-ignition of the main bumer(s). 

It is permissible to supervise flames at the intersection of the main burner flame and the pilot flame rather than providing supervision equipment for both, as long as the pilot flame is interrupted after ignition trial of the burner, per NFPA 86 (sect. 5-9.2.1). 

Operational Problems of the Pilot Plant. Pilot plant operation began in late August 1971 and initially investigated treatment of a 12% sulfur dioxide gas stream. A number of minor start-up problems were resolved, and a relatively stable, around-the-clock operation was achieved by mid-September. Operation in this mode continued, with some interruptions, until late February 1972. During this period 91 days of operation were logged. Typically, sulfur recoveries averaged 88-92% as compared with a theoretical recovery of approximately 93%. Eleven days of downtime were attributed to curtailed industrial use of natural gas. Other than this, most of the downtime was caused by two problems. 

Pilot type and flame establishing period N/A Interrupted 10 sec maximum Interrupted 10 sec maximum... 

After these laboratory investigations, pilot plant trials were carried out on a modified process. After formation of the monolithium acetylide in stage I, ammonia is distilled off and replaced by solvent I. The distillative removal of ammonia must be carried out at a controlled heating rate so that the monolithium acetylide-ammonia complex, which is not very stable, does not decompose. The distillation is interrupted at exactly 5 °C. In order to facilitate drying of the solvent, a further solvent change is carried out after condensation, since solvent II can easily be dried and is also used in the following step of the process [213],... 

The design of incremental control algorithms can become complex when a human controller is controlling a computer, which is controlling the actual physical process, in a stressful and busy environment, such as a military aircraft. If one of the commands in an incremental control sequence cannot be executed within a specified period of time, the human operator needs to be informed about any delay or postponement or the entire sequence should be canceled and the operator informed. At the same time, interrupting the pilot with a lot of messages that may not be critical at a busy time could also be dangerous. Careful analysis is required to determine when multistep controller inputs can be preempted or interrupted before they are complete and when feedback should occur that this happened [90]. 

Unavailable Service characterized by the interruption of the control services, due to either an unavailability of any critical infrastructure (i.e. controller-pilot communications, power, etc.) or critical unavailability of human resources for operation. 

But should this trip be permanently removed The determining factor in answering this question is the response taken by the operators when both air and hydrogen sulfide flows were interrupted. They did not reestablish combustion by relighting the pilot light, as the designers envisioned. This would have taken many hours and was hence impractical. The operators proceeded as follows ... 

Brazilian Copersucar used to supply samples of PHB in quantities of few hundreds of kilograms produced in a pilot plant connected with a sugar production. Although the purity of the product was not the best the material was suitable for many purposes. After some interruption of production in 2000, they stopped supplying free samples and they seem to be more or less sold out, supplying only to various small customers, apparently to research laboratories and some companies using the material for special purposes [55]. The purity of the product and the quality standard over a long... 

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