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SQL QUERY FAILURE:SELECT COUNT(*) FROM xcart_sessions_data WHERE sessid='eac5d09ada7daddc65b5ef61e14b1fa9'
INVALID SQL: 145 : Table './web24@002dmaint/xcart_sessions_data' is marked as crashed and should be repaired
SQL QUERY FAILURE:SELECT COUNT(*) FROM xcart_sessions_data WHERE sessid='c1c5c2a40ebfa74cb859fb01781d327e'
INVALID SQL: 145 : Table './web24@002dmaint/xcart_sessions_data' is marked as crashed and should be repaired
SQL QUERY FAILURE:SELECT sessid FROM xcart_sessions_data WHERE expiry < '1337751766'
INVALID SQL: 145 : Table './web24@002dmaint/xcart_sessions_data' is marked as crashed and should be repaired
SQL QUERY FAILURE:SELECT * FROM xcart_sessions_data WHERE sessid='c1c5c2a40ebfa74cb859fb01781d327e'
INVALID SQL: 145 : Table './web24@002dmaint/xcart_sessions_data' is marked as crashed and should be repaired
SQL QUERY FAILURE:REPLACE INTO xcart_sessions_data (sessid, start, expiry, data) VALUES('c1c5c2a40ebfa74cb859fb01781d327e', '1337751766', '1337755366', 'a:0:{}')
INVALID SQL: 145 : Table './web24@002dmaint/xcart_sessions_data' is marked as crashed and should be repaired
SQL QUERY FAILURE:UPDATE xcart_sessions_data SET data='a:6:{s:17:\"_saved_session_fg\";s:32:\"0d63ba59e80a8e5230f9f147c35dc88a\";s:11:\"editor_mode\";s:0:\"\";s:8:\"is_robot\";s:1:\"N\";s:5:\"robot\";s:0:\"\";s:11:\"is_location\";s:0:\"\";s:9:\"adaptives\";a:1:{s:14:\"is_first_start\";s:1:\"Y\";}}' WHERE sessid='c1c5c2a40ebfa74cb859fb01781d327e'
INVALID SQL: 145 : Table './web24@002dmaint/xcart_sessions_data' is marked as crashed and should be repaired
SQL QUERY FAILURE:UPDATE xcart_sessions_data SET data='a:7:{s:17:\"_saved_session_fg\";s:32:\"0d63ba59e80a8e5230f9f147c35dc88a\";s:11:\"editor_mode\";s:0:\"\";s:8:\"is_robot\";s:1:\"N\";s:5:\"robot\";s:0:\"\";s:11:\"is_location\";s:0:\"\";s:9:\"adaptives\";a:1:{s:14:\"is_first_start\";s:1:\"Y\";}s:22:\"antibot_validation_val\";a:3:{s:13:\"on_contact_us\";a:2:{s:4:\"code\";s:5:\"14924\";s:4:\"used\";s:1:\"N\";}s:15:\"on_registration\";a:2:{s:4:\"code\";s:5:\"43333\";s:4:\"used\";s:1:\"N\";}s:10:\"on_reviews\";a:2:{s:4:\"code\";s:5:\"82954\";s:4:\"used\";s:1:\"N\";}}}' WHERE sessid='c1c5c2a40ebfa74cb859fb01781d327e'
INVALID SQL: 145 : Table './web24@002dmaint/xcart_sessions_data' is marked as crashed and should be repaired
SQL QUERY FAILURE:UPDATE xcart_sessions_data SET data='a:30:{s:17:\"_saved_session_fg\";s:32:\"0d63ba59e80a8e5230f9f147c35dc88a\";s:11:\"editor_mode\";s:0:\"\";s:8:\"is_robot\";s:1:\"N\";s:5:\"robot\";s:0:\"\";s:11:\"is_location\";s:0:\"\";s:9:\"adaptives\";a:1:{s:14:\"is_first_start\";s:1:\"Y\";}s:22:\"antibot_validation_val\";a:3:{s:13:\"on_contact_us\";a:2:{s:4:\"code\";s:5:\"14924\";s:4:\"used\";s:1:\"N\";}s:15:\"on_registration\";a:2:{s:4:\"code\";s:5:\"43333\";s:4:\"used\";s:1:\"N\";}s:10:\"on_reviews\";a:2:{s:4:\"code\";s:5:\"82954\";s:4:\"used\";s:1:\"N\";}}s:23:\"offer_products_priority\";a:0:{}s:4:\"cart\";s:0:\"\";s:5:\"login\";s:0:\"\";s:10:\"login_type\";s:0:\"\";s:18:\"new_offers_message\";a:1:{s:7:\"content\";s:566:\" <div align=\"center\"> <table cellpadding=\"5\" cellspacing=\"0\" width=\"95%\"> <tr> <td align=\"center\" width=\"33%\"> New special offers are available! </td> <td>&nbsp;</td> <td>&nbsp;</td> </tr> <tr> <td align=\"right\" colspan=\"3\"> <hr class=\"Line\" size=\"1\" /> <table cellspacing=\"0\" cellpadding=\"0\"> <tr> <td><a class=\"NavigationPath\" href=\"offers.php\">more offers</a></td> <td><a class=\"NavigationPath\" href=\"offers.php\"><img src=\"/maint/skin1/images/offerbox_arrow.gif\" alt=\"\" /></a></td> </tr> </table> &nbsp; </td> </tr> </table><!-- border --> </div> <br /> \";}s:25:\"customer_available_offers\";a:2:{i:0;s:1:\"1\";i:1;s:1:\"2\";}s:11:\"logout_user\";s:0:\"\";s:26:\"session_failed_transaction\";s:0:\"\";s:16:\"add_to_cart_time\";s:0:\"\";s:17:\"always_allow_shop\";s:0:\"\";s:11:\"search_data\";s:0:\"\";s:10:\"session_ip\";s:14:\"38.107.179.217\";s:16:\"current_url_page\";s:59:\"http://www.system-maintenance.com/maint/pages.php?pageid=36\";s:12:\"current_date\";i:1337751766;s:19:\"session_create_date\";i:1337751766;s:4:\"wlid\";s:0:\"\";s:10:\"js_enabled\";s:1:\"Y\";s:11:\"top_message\";s:0:\"\";s:15:\"referer_session\";b:0;s:11:\"identifiers\";a:0:{}s:6:\"logged\";s:0:\"\";s:14:\"remember_login\";b:0;s:13:\"remember_data\";s:0:\"\";}' WHERE sessid='c1c5c2a40ebfa74cb859fb01781d327e'
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20-03-2012

Do you want a control system designing for your new or existing project ?

If yes, then all you have to supply is a description of operation and an Input/Output points list, and i will do the rest.

For your FREE no obligation quote go to http://bms.system-maintenance.com or http://tridium.business-maintenance.com and enter some basic information into the online contact form.

A little about me, I am a Tridium certified controls programmer and have a HND in electrical / electronic engineering as well as being 17th edition wiring regulations certified. I have a valid JIB CSCS card so there is no problem with goning onto any construction site / site inductions.

As well as working on a daily basis with the Tridium Niagara platform I also work with touch screen HMI (Maple Systems) and Seimens LOGO plc for small projects.
I have designed projects from small underfloor heating systems for domestic houses to large complex commercial heating and cooling systems, so no job is to smal or to large.

I have designed software for Kier, Balfour Beatty plc, BAM, Land Securities and many more large companys.

So just give me a try for your control design software, you will be happy with the design as well as the price, thats a promise.

Waiting for your to contactnme, regards Paul.



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HVAC Formulas

Dewpoint and Wetbulb Temperature

The following equations are used to calculate the wetbulb temperature of air given the drybulb temperature and relative humidity %. The equation assumes that the ambient barometric pressure is constant at a value of 29.15 “Hg since the change in wetbulb temperature is very insignificant with changes in the ambient barometric pressure.

Input Variables System Variables Output Variables
RH Relative Humidity % e Ambient vapor pressure in kPa Td Dewpoint temperature in degrees C
T Drybulb temperature in degrees C GAMMA Constant based upon ambient barometric pressure Tw Wetbulb temperature
    DELTA Constant    
Equations
e (RH / 100) * 0.611*EXP(17.27*T/(T+237.3))
Td [116.9 + 237.3 ln(e)] / [16.78 – ln(e)]
GAMMA 0.00066*P (Use P = 98.642 kPa. This is equal to 29.15 “Hg… about the pressure we normally experience.)
DELTA 4098*(e / Td + 237.3)^2
Wetbulb Temperature in Degrees F Equals:
Tw 1.8 * [[(GAMMA*T) + (DELTA*Td)] / (GAMMA + DELTA)] + 32
Dewpoint Temperature in Degrees F Equals:
Td 1.8 * [[116.9 + 237.3 ln(e)] / [16.78 – ln(e)]] + 32

Air Handling Unit Tonnage Output

The following equation calculates the refrigeration output in Tonns of a coil.

Input Variables Output Variables
T1 Entering air temperature of the coil in degrees F TONNS Dewpoint temperature in degrees F
T2 Leaving air temperature of the coil in degrees F    
CFM Volume of air passing through the coil    
Equation
TONNS 1.08*(T1 – T2)*CFM

Chiller Tonnage Output

The following equation calculates the refrigeration output in Tonns of a chiller.

Input Variables Output Variables
T1 Chilled water return temperature in degrees F TONNS Energy output of the chiller
T2 Chilled water supply temperature in degrees F    
GPM Volume of water passing through the chiller    
Equation
TONNS GPM*(T1 – T2) / 24

Chiller Coefficient of Performance

The following equation calculates the ratio of energy used to the energy output of a chiller.

Input Variables
T1 Chilled water return temperature in degrees F
T2 Chilled water supply temperature in degrees F
GPM Volume of water passing through the chiller
KW Kilowatts
Output Variables
COP Energy output of the chiller
Equation
COP (T1 – T2) * GPM * 0.0417 / (0.28433 * KW)

VAV Box Air Flow Rate (CFM)

Input Variables
A Duct area in sq. ft
Pv Pressure in inches of H2O from PV3
Output Variables
V Velocity of the air
CFM Cubic feet of air per minute
Equation
Q AV
0.0763 is the density of dry air at 60o F
The duct diameter units are in ft.
CFM 1096Π(Duct Diameter/2)2(√(Pv/.0763))

Heat Index Calculation

The following equation calculates the heat index of the outside air.

Input Variables
Tf Outside air temperature in degrees F
RH Outside air relative humidity % (enter 50 for 50%, etc.)
Output Variables
HI Heat index

Wind Chill Temperature Calculation

The following equation calculates the wind chill temperature of the outside air.

Input Variables
V Outside air velocity in Miles per Hour
T Outside air temperature in degrees F
Output Variables
WC Wind chill temperature
Equation
WC 0.0817(3.71(V)^0.5 + 5.81 - 0.25V)(T - 91.4) + 91.4

Pressure Measurement

Velocity Pressure
Where V = Air Velocity (FPM)
Pv = Velocity Pressure (in. w.g.)
Equivalent Measures of Pressure
1lb. per square inch = 144lbs. per sq. ft.
= 2.036in. Mercury at 32°F
= 2.311ft. Water at 70°F
= 27.74in. Water at 70°F
1 inch Water at 70°F = .03609lb. per sq. in.
= .5774oz. per sq. in.
= 5774oz. per sq. in.
= 5.196lbs. per sq. ft.
1 ounce per sq. in. = 1272in. Mercury at 32°F
= 1.733in. Water at 70°F
1ft. Water at 70°F = .433lbs. per sq. in.
= 62.31lbs. sq. ft.
1 Atmosphere = 14.696lbs. per sq. in.
= 2116.3lbs. per sq. ft.
= 33.96ft. Water at 70°F
= 29.92in. Mercury at 32°F
1in. Mercury at 32°F = .491lbs. per sq. in.
= 7.86oz. per sq. in.
= 1.136ft. Water at 70°F
= 13.63in. Water at 70°F
Compression Ratio
Compression Ratio = Absolute Discharge Pressure / Absolute Suction Pressure
Absolute Discharge Pressure = gauge reading + 15psi
Absolute Suction Pressure = gauge reading + 15psi

Refrigerant Mass Flow Rate
Mass Flow Rate
(Pounds/Minute)		 = Piston Displacement X Refrigerant Density
= (Cubic Feet/Minute) X (Pounds/Cubic Feet)

 
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INVALID SQL: 145 : Table './web24@002dmaint/xcart_sessions_data' is marked as crashed and should be repaired
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