Duct detector

Duct detector Is located within the heating and ventilation ducts of the facility. This sensor detects the presence of smoke within the system s return or supply ducts. A sampling tube can be added to the detector to help span the width of the duct. 

All systems should receive a visual inspection each quarter. Test or inspect each antomatic system on an annual basis. Include all systems in the preventive maintenance plan. Test all snpervisory signal devices except valve tamper switches on a quarterly basis. Test valve tamper switches and water flow devices semiannually. Test duct detectors, electromechanical releasing devices, heat detectors, manual fire alarm boxes, and smoke detectors on a semiannual basis. Test occupant alarm notification devices to inclnde andible and visible devices at least annually. Maintain appropriate documentation on all tire-related system testing. 

Flevated or Remote Air Intakes Elevated or remote air intakes for control rooms will help in reducing ingress of dense, flammable vapors into those rooms. Ordinarily, elevating the tip of the air intake duct 9 m (30 ft) above the ground is sufficient. Installing flammable vapor detectors in the air intake ducts provides additional protection. Controls that automatically stop air to control rooms if vapor concentrations reach 25 percent of their LFL should also be considered. 

Other properties of solvents which need to be considered are boiling point, viscosity (lower viscosity generally gives greater chromatographic efficiency), detector compatibility, flammability, and toxicity. Many of the common solvents used in HPLC are flammable and some are toxic and it is therefore advisable for HPLC instrumentation to be used in a well-ventilated laboratory, if possible under an extraction duct or hood. 

The concrete block walls of the cell housing the generator tube and associated components are 1.7 meters thick. The facility also includes a Kaman Nuclear dual-axis rotator assembly for simultaneous transfer and irradiation of reference and unknown sample, and a dual Na iodide (Nal) scintillation detector system designed for simultaneous counting of activated samples. Automatic transfer of samples between load station to the rotator assembly in front of the target, and back to the count station, is accomplished pneumatically by means of two 1.2cm (i.d.) polyethylene tubes which loop down at both ends of the system and pass underneath the concrete shielding thru a pipe duct. Total one-way traverse distance for the samples is approx 9 meters. In performing quantitative analysis for a particular element by neutron activation, the usual approach is to compare the count rates of an unknown sample with that of a reference standard of known compn irradiated under identical conditions... 

Applications. The munitions industry has several applications suited for infrared detectors. Conveyor belts passing through large covered ducts and explosive and propellant mixers are examples of the controlled environment necessary for proper application. 

PGDN was generated from a sample of Otto Fuel II by blowing air across a Pyrex reservoir of the compound to the return air duct of the air conditioner. Eighty percent of the air was recirculated. The concentration of PGDN in the air was monitored continuously by an infrared spectrophotometer and by a gas chromatograph fitted with an electron capture detector. The vaporized Otto Fuel II was 99% pure PGDN as measured by infrared analysis. 

Point Combustible Gas Detectors (IR) are used to indicate the presence of gas at a particular location (e.g., in a congested area of the planter in small ducts.) IR technology has proven to be more reliable than catalytic bead detectors. The point detector functions in the same manner as the open path detector, by comparing absorbed and reference frequencies of IR light. The main difference between these and open path type is that the path length of the point type is short (3 inches) and is kept within the confines of the instrument. 

A water-cooled sampling probe of internal diameter 1 mm and external diameter 5 mm with a 3-meter long heated line was used to measure concentrations of unburned hydrocarbon (flame ionization detector, Analysis Automation, 520) and NOj (chemiluminescence analyzer, Thermal Environment Instruments, 42) at the combustor exit on a wet basis. The former, measured to a precision of the order of 1 ppm, was used to ensure complete consumption of fuel within the duct, and the latter with a precision of around 0.2 ppm was used to quantify the effect of oscillations on NOj. emissions. 

Figure 24.2 Schematic diagram of the setup used to measure and control H2O concentration and gas temperature in the combustion region (in situ) of a forced 5-kilowatt combustor at Stanford University 1 — steel duct 2 — quartz duct 3 — A1 duct 4 — multiplexed beam 5 — tunable diode lasers 6 — data acquisition and control computer 7 — control signals 8 — primary air driver Aair sin(27r/of) 9 — fuel drivers Afuei sin(27r/of-f dfuei) 10 — demultiplexing box 11 — Si detector (ND filter) and 12 — laser beam...

Jet deflection flow detectors can be considered for flow measurement in large, low-pressure, circular, or rectangular ducts. If they are used in stacks... 

The ventilated air and gaseous waste from the controlled area are released through the stack after dealing with high efficiency particulate air filters. There are two methods of continuously monitoring the concentration in exhaust gas. One is to measure the gas directly with a detector inserted into the stack or duct and the other is to measure a portion sampled from the exhaust air with a dust monitor or a gas monitor. 

Gases from emissions may be measured by placing sensors in the gas stream. Or they may be measured remotely spectrophotometrically via a fight beam that traverses the exhaust gas and is reflected back to the detector. Extractive sampling may be done by inserting a sampling probe tube in the duct and pumping gas to the analyzer or sample collection device. 

Typical records obtained from slurries are shown in Figs. 6.26 and 6.27. The variation of the signal profile can be explained by different flow models (Porges, 1984). The averaged flow velocity can be derived from the PNA signal recorded by the detector at a known distance downstream from the PNA source. The PNA velocity results agreed with timed-diversion measurements to within 0.5% and no systematic deviation was found. We believe that the accuracy achieved by the PNA technique can be better than that obtained by other techniques because the PNA system irradiates the entire duct, and the shape of the readout is directly related to the motion of the tags. 

Principal Component REACTOR SERVICES GROUP (Continued) Core and Service Facility Tools Neutron Detector Service Equipment Hot Duct Seirvice Equipment... 

Combustible gas detectors are generally installed in buildings and in the intakes to the HVAC air ducts. They can also be installed in outdoor areas that could have hydrocarbon vapor present, particularly remote areas such as truck unloading stations that may not have personnel present all the... 

Confirm working of all safety devices, safety interconnections, overload trip settings, working of effluent treatment plant (along with availability of chemicals for treatment) DG sets, cooling systems for reactors and condensers lire fighting pumps, gas detectors, etc. Clean (flush) all the pipelines and ducts. Check all other equipments required for the particular plant. All instmments and process controllers shall be calibrated and tested. 

Hand-held (portable) infrared temperature detectors for detecting heat loss from furnace shell or gas ducts, temperatures of bearings (can indicate need for immediate cleaning and lubrication), and electrical bus bars (can indicate loose contacts) ... 

Inlet and outlet ducts close automatically when pressure exceeds limit. Eadiation detector haust line. Excessive air contamination will sound alarm permitting manual closing of roof vents from 10 -H control room. 

---