Author: Site Editor Publish Time: 2021-11-19 Origin: Site
Manholes are important elements to cities, communities and properties as they serve as an access point for gages and meters that are indispensable to maintaining the flow of water. Also, manholes allow access to maintenance workers to inspect and repair underground piping and telecom lines.
Manhole covers can often be made of different materials and into various sizes, shapes and designs.
Manholes have a few similarities most especially in functions, however, they also have a couple of differences.
Today, we are going to introduce BMC Manhole Cover and SMC Manhole Cover.
What are the advantages and disadvantages of each manhole cover?
Which one is more effective for your job?
Don't worry! Read this article and find your answers.
Let's begin with "BMC" and "SMC".
BMC: abbreviation of Bulk Moulding Compound (BMC)
SMC: abbreviation of Sheet Moulding Compound (SMC)
Bulk molding compound (BMC), bulk molding composite, or dough molding compound (DMC), is a ready-to-mold, glass-fiber reinforced thermoset polymer material primarily used in compression molding, as well as in injection molding and transfer molding. Typical applications include demanding electrical applications, corrosion resistant needs, appliance, automotive, and transit.
BMC is manufactured by mixing strands (Greater than 1/8 and less than 2) of chopped glass fibers, styrene, an initiator, and filler in a mixer with an unsaturated thermoset resin (commonly polyester resin, vinyl ester resin or epoxy resin). The mixing is done at room temperature and stored at low temperatures to slow down curing prior to molding. The concentration of the mixture can vary depending on application but is typically 30% glass fibers, 25% filler, and 45% resin, styrene, and initiator. The material is provided in bulk or in logs approximately 4 in diameter. The glass fibers in BMC increase the strength properties of the product to be higher than standard thermoplastic products.
(From Wikipedia)
Sheet molding compound (SMC) or sheet molding composite is a ready to mold glass-fiber reinforced polyester material primarily used in compression molding. The sheet is provided in rolls weighing up to 1000 kg. Alternatively, the resin and related materials may be mixed on-site when a producer wants greater control over the chemistry and filler.
SMC is both a process and a reinforced composite material. This is manufactured by dispersing long strands (usually >1) of chopped fiber, commonly glass fibers or carbon fibers on a bath of thermoset resin (typically polyester resin, vinyl ester resin or epoxy resin). The longer fibers in SMC result in better strength properties than standard bulk molding compound (BMC) products. Typical applications include demanding electrical applications, corrosion resistant needs, structural components at low cost, automotive, and transit.
(From Wikipedia)
Manhole covers made from these two composite materials have many advantages in common.
Environmental protection
Two materials are environmentally friendly.
Lightweight
Generally, a cast iron manhole is 2/3 heavier. Comparatively, BMC and SMC manhole covers are more convenient to construct, transport, install, replace and repair.
Longevity
BMC and SMC manhole covers have the advantages of high strength and good electrical insulation properties, aging resistance, acid and alkali resistance, impact resistance. They can last around 20 years in regular use.
Anti-theft
BMC and SMC are not recyclable, hence BMC and SMC manhole covers are naturally anti-theft.
Competitive price
The price of a compound manhole cover is lower than cast iron ones.
The structure of the BMC manhole cover and the SMC manhole covers are different.
The BMC manhole cover has the cross rebar inside the compound material, which is used to enhance its strength. However, a crack may occur between the rebar and the surrounding material, which will never happen to the SMC manhole cover. Therefore, the SMC manhole cover reduces the risk of crack.
If you have any other problems, don't hesitate to consult Jinmeng! Jinmeng will dispel your confusion.
