A Review of Main Factors Leading to Air Pressure Fluctuations in Branch Drainage Pipes inside Buildings

This paper is to discuss the main factors leading to the air pressure fluctuations in appliance branch pipes and measures to control them. It has been established that the main factors characteristics of a good sanitary pipework system are that it must prevent the transmission of foul air into the building, minimize blockages, provide efficient conveyance of discharge from sanitary appliances and minimize the risk of flooding to any part of a building. However, due to the nature and properties of sanitary appliance discharge, the flow being a three-phase flow which is simplified to two-phase for design computations and discharge being probabilistic, air variations in the horizontal appliance pipe result in phenomenon in which the sanitary network fails to perform as designed and installed to prevent or minimize aforementioned circumstances. It has been established that the main factors to be discussed leading to air pressure fluctuations in the appliance branch pipe are water traps, bend structures, pipe diameter, pipe slope and length, angle and connection mode and ventilation conditions. These factors’ associated control measures have also been presented. However, factors pertaining to concentration of appliance discharge have not been discussed. The result of this discussion will enable designers and installers of sanitary pipework to incorporate measures to control air pressure fluctuations in appliance branch pipes inside buildings.

Effects of dynamic segmentation of nutrient supply on growth performance and intestinal development of broilers

This experiment was to investigate the effects of dynamic segmentation of interval nutrient supply phase feeding on the growth performance, carcass characteristics, immune organs indexes and intestinal morphology of broilers. A total of 320 one-day-old broilers were randomly assigned into 4 feeding treatments, which included 4 interval nutrient supply phases as follows. Treatment A: a nutrient supply standard was used for every 14 d. Treatment B: a nutrient supply standard was used for every 7 d. Treatment C: a nutrient supply standard was used for every 3.5 d except that one nutrient supply standard was used for d 1 to 7. Treatment D: a nutrient supply standard was used for every 3.5 d including d 1 to 7. Each treatment was represented by 8 replicates with 10 broilers per replicate. The trial lasted for 42 days. Throughout the 42 d trial period, treatment A showed significantly higher average daily gain than treatments B and C(P < 0.05). The feed:gain ratio of treatment A was significantly lower than those of treatments C and D(P < 0.05). On d 28 and 42, body weight of broilers in treatment A was much higher than those of treatments B and C(P < 0.05). The slaughter rate of treatment A was significantly higher than that of treatment B(P < 0.05). Eviscerated percentage of treatment A was significantly higher than those of treatment B and D(P < 0.05). There were no significant differences among 4 treatments in immune organs indexes(P > 0.05). The crypt depth of duodenum was significantly greater in treatments A and B than in treatment C on day 42(P < 0.05).Meanwhile, the ratio of villus height to crypt depth(V:C ratio) of treatment D was significantly higher than that of treatment A(P < 0.05). No significant differences were found between treatments C and D in growth performance, carcass performance, immune organs indexes and intestinal structure(P> 0.05). In conclusion, this study revealed that the growth and carcass performance of broilers is the best for 14 days segmentation phase feeding, and 3.5 days segmentation interval phase feeding can promote small intestinal development of broilers. Dynamic segmentation of dietary supply fails to affect the immune function of broilers.