Wednesday, October 28, 2015

water pipe


Water pressure: 80 psi
The most common source of excessive water pressure is the municipal water supplier. The water company sets the pressure to meet their own needs, such as delivering water to fire hydrants, high elevation buildings (or tall ones), and other reasons. This water pressure is often well over 100 psi, and too often over 150 psi. However, the maximum recommended pressure for a residence is 80 psi.

Copper pipe:
½ L : 1,200 psi
1/2 L :  1,000 psi
¾ M : 700 psi
½ ,3/8, ¾ Coil : 360 psi

Plastic coil pipe:
100 psi   ,
Usage: Landscape and agricultural irrigation, residential and commercial water service, well/pump water systems

CPVC pipe:  
100 psi
Usage: CPVC Ultra-Pure is used for hot and cold water systems
Temp: [ 33F, 180F]  or   [ 0c, 80c]
Size : measure OD ( outside diameter )
Advantage : as durable as copper  and stand up high temperature and pressure.
Used to transition from metal piping systems to CPVC
Used to transition from metal male pipe threads to CPVC.

PVC pipe:
280 psi
Size : measure ID ( inside diameter)
Usage: Pressure and drain, waste and vent

Schedule 40 : The most common Schedules are 40, 80 and 120, with Schedule 40 being the most readily available and commonly used. As the schedule gets larger the pipe wall gets thicker from the outside in, so the inside hole (bore) of the pipe gets smaller.


Adapter from copper to CPVC.
        
         
Use Compression Fittings on copper and PEX tubes.  
     
     
   
 
Use Compression Fittings on copper tubes
     





 

Prevent nail from drilling thru. pipe


 

Use PEX in bathroom remodel 









                                                                 




PEX pipe: Apollo 1/2-in x 25-ft 160-PSI PEX Pipe
160 psi
30F < temp < 200F

Its pressure rating is even higher than CPVC, therefore it’s more suitable to replace copper pipe in bathroom or kitchen remodel projects.

Advantage: it’s more flexible.  Use clip ring can easily clip into shower header, etc. 
$30 / 1/2inch 100 ft  pex pipe
50C / crimp ring
80C / coupling fitting

      


Home basics

Home is all about how to take care of Water & fire/electricity. Once these two things are well taken care of, then the house should be in a good shape.

So it’s very important to know these basic information about water-related and electrical components used in your home.


Home =  water + electricity


1.  water pipe  
2.   todo




Saturday, October 24, 2015

GRIB2

GRIB:  GRIdded Binary
          data in the form of grid-point values expressed in binary form


GRIB1 v.s. GRIB2


  1. GRIB1 Product Definition Section into the GRIB2 Identification, Product Definition, and Data Representation Sections.
  2. Option for iterating the Sections and expansion of the concept of templates.


A single GRIB2 message structure:
Definition of A field in a GRIB2 message:
     a grid ,    for example, ht@500mb for fhr 12.


eg: If there are 500 hPa height field forecasts on a Northern Hemisphere polar
stereographic grid produced by a particular numerical model at forecast hours 12, 24, 36, and 48, then we have 4 fields, which can be saved in one single GRIB2 message.




EG: 500 hPa height field forecasts produced at forecast 24 hours on
four different grid projections.




GrADS and GRIB2

 
wgrib : for GRIB1 
wgrib2 : for GRIB2
 
Relationship (Data descriptor : *.ctl files) between GRIB2 and GrADS: 
# ctl name don't matter, but better use cmd below.
$ g2ctl.pl gfs.t00z.pgrb2.0p25.f000 > abc.ctl
$ g2ctl.pl gfs.t00z.pgrb2.0p25.f000 > gfs.t00z.pgrb2.0p25.f000.ctl

 
Explanation of "PRES 0 1, 102,0 Pressure[Pa]" :
1) space deliminator, so it's four parts: PRES / 0 / 1,102,0 / Presssure[Pa]
2)
PRES: name of parameter
0 : 1 level on surface
1,102,0 : parameter description, see below ( VV, LTYPE, LEVEL,TRI)
Pressure[Pa]: unit


Eg of VV, LTYPE, (LEVEL), (TRI):
1, 102, 0 n/a
33, 100 n/a n/a
34, 100 n/a n/a

VV:
1 : pressure
33: wind u component
34: wind v component
LTYPE:
100 : pressure level
102 : mean sea level
(LEVEL)
0 : mean sea level

(TRI)
n/a

Explanation: 
1, 102, 0 : mean sea level pressure

 
Index file (.idx) : tell where fields in GRIB2 are located.
$ gribmap -v -i gfs.t00z.pgrb2.0p25.f000.ctl > grib2_field_vs_grads_var

Note : 1) binary file "gfs.t00z.pgrb2.0p25.f000.idx" will be generated. 
2) Input GRIB2 file "gfs.t00z.pgrb2.0p25.f000" must be present.