

$ST Hot stream 1:
$ST Cold stream 2:
$ST Stream
$SI Shellside:
$SI Tubeside:
$SI X-side:
$SI
$IO inlet
$IO outlet
$
$M001
 *** WARNING *** The following input item(s) are beyond the expected range:
$M002
 ** FATAL ERROR ** The following input item(s) are beyond the permitted range:
$M003
 ** FATAL ERROR ** No data input provided for the following item(s):
$M004
 ** FATAL ERROR ** The following data input item(s) are unacceptable:    
$M005
 *** WARNING *** The following lines in the input are unrecognised:
$M006
 *** WARNING *** There are unrecognised characters on this line.$NL
 Some or all input on this line is ignored.
$M010
 *** WARNING *** An output message is not available in the message file. Contact
 HTFS. $NL $I1 $I2 $I3 $I4 $R1 $R2 $R3 $R4 $$ 


$M011
 *** WARNING *** $ST $SI $IO Temperature $R1 and quality $R2 at pressure $R3   
 are inconsistent. Quality has been reset to $R4. [CURV 1906,2906] $$
$M012
 *** WARNING *** $ST $SI $IO Temperature $R1 and quality $R2 at pressure $R3   
 are inconsistent. Temperature has been reset to $R4 $$
$M013
 *** WARNING *** $ST $SI $IO Boiling point $R1 and pressure $R2 are not     
 consistent. Boiling point used is $R3. Saturation pressure at $R1 is $R4. $NL
 You may wish to revise this temperature or pressure, or revise 
 temperatures / pressures in the property data input. If the property data are
 calculated or from a databank, you can use the T-h-x over-ride, in the
 property data input, to force them to be consistent with your process data
 [CURV 1907,2907] $$
$M014
 *** WARNING *** $ST $SI $IO There is a small inconsistency in the temperature
 / enthalpy interpolation. Temperature has been reset from $R1 to $R2. $$
$M015
 ** FATAL ERROR ** $ST $SI Neither inlet nor outlet conditions have been input.
 Specify at least three of the following. $NL Inlet temperature; Outlet 
 temperature; Flowrate; Heat Load. $$
$M016
 ** FATAL ERROR ** $ST $SI Only inlet or outlet conditions have been specified,
 but no flow rate. Specify at least three of the following. $NL 
 Inlet temperature; Outlet temperature; Flowrate; Heat Load. $$
$M017
 *** WARNING *** $ST $SI $IO The heat load of $R1 specified in the input has
 been changed to $R2, to agree with the outlet conditions specified (or
 defaulted) in the input. $NL To avoid this change of heat load, omit the outlet
 temperature and quality from the input data, or specify a heat balance flag
 (input item 205.1) of 3,4, or 5.
$M018
 ** FATAL ERROR ** $ST $SI A very small or zero heat load has been calculated.  
 The inlet quality is $R1, the outlet quality is $R2. Check that inlet/outlet
 temperatures and qualities specified in the Process Data input are consistent
 with Physical Property data.  Also check the mass flowrate.
 $NL You can force the Properties data to be consistent, by using the T-h-x
 over-ride facility in the Properties input.. 
$M019
 *** WARNING *** $ST $SI $IO The temperature calculated from your input 
 enthalpy ($R1) and pressure ($R2) is $R3, which differs from your input
 temperature ($R4). The calculated value is used.
$M020
 *** WARNING *** $ST $SI $IO The quality (vap.mass frac.) calculated from your
 input enthalpy ($R1) and pressure ($R2) is $R3, which differs from your input
 quality ($R4). The calculated value is used.

$M021
 ** FATAL ERROR ** No heat loads specified for either stream, nor can they be 
 calculated from flowrates and inlet and outlet conditions. [CURV 3602] $$
$M022
 ** FATAL ERROR $ST Inlet conditions and flowrates not input, and cannot be 
 calculated. Both are required in SIMULATION mode. %% 
$M023
 ** FATAL ERROR ** $ST $SI Temperature changes from $R1 at inlet to $R2 at 
 outlet. $NL Hot streams should get colder, and cold streams hotter. $$
$M024
 ** FATAL ERROR ** Temperature cross. $ST $SI Outlet temperature is $R1.
 For the other stream, the inlet temperature is $R2. 
$M025
 ** FATAL ERROR ** Serious mis-match of heat loads. $ST $SI Heat load is $R1.
 For the other stream, the heat load is $R2. [CURV 3604] $$

$M026
 ** FATAL ERROR ** Heat loads differ by more than 10 %. 
 $ST $SI Heat load is $R1. For the other stream, the heat load is $R2.
 [CURV 3601] $$
$M027 
 *** WARNING *** Heat loads differ by more than 1 %. $NL
 $ST $SI Heat load is $R1.
 For the other stream, the heat load is $R2. The ratio of the larger load to
 the mean load is $R3. $NL
 The program uses the mean heat load, and adjusts individual stream enthalpies 
 to give the specified inlet and outlet conditions. [CURV 3501] $$
$M028 
 *** WARNING *** Initial heat loads from input differ by more than 1 %. 
 A revised initial heat load of $R1 has been selected, giving initial
 estimates of outlet temperatures of $R2 for stream 1 and $R3 for stream 2.
 $$
$M029 
 ** FATAL ERROR ** $ST $SI The specified leakage fraction is such that, in
 order to achieve the specified heat load, the remainder of the stream would 
 need to achieve a temperature of $R1 in the shell, which is impossible, 
 given the tubeside inlet temperature of $R2. [CURV 1804] $$
 
$M031
 *** WARNING *** $ST $SI Boiling of the cold stream is expected. Since the 
 boiling methods require surface tension, a default value, as shown in a
 preceding warning has been assumed in some calculations. If you wish to revise
 this value, specify the new value(s) with the liquid properties input 
 (line 316) for the cold stream. $$  
$M032
 *** WARNING *** Approximations are made for the tubeside temperature profile 
 in DESIGN mode. These approximations are reasonable for most cases, but
 sometimes the results may be inaccurate for cases which are two phase on the
 tubeside, especially if the tubeside heat transfer coefficient varies
 significantly. Please check the design in CHECKING mode. [CURV 3702] $$
$M033
 *** WARNING *** In DESIGN mode, TASC3 can only handle a maximum of 4 tubeside 
 passes per shell pass (E,F or K shells), when the flow is two phase on the 
 tubeside. The maximum number of tubeside passes has been changed from $I1 to 
 4. [CURV 3703] $$
$M034
 *** WARNING *** In DESIGN mode, TASC3 can only handle a maximum of 2 tubeside
 passes per shell pass (I,J or G shells), when the flow is two phase on the 
 tubeside. The maximum number of tubeside passes has been changed from $I1 
 to 2. [CURV 3704] $$
$M035
 ** FATAL ERROR ** In CHECKING or SIMULATION modes, TASC3 can only handle a 
 maximum of 4 tubeside passes per shell pass (E,F or K shells), when the 
 flow is two phase on the tubeside. [CURV 3801] $$
$M036
 ** FATAL ERROR ** In CHECKING or SIMULATION modes, TASC3 can only handle a 
 maximum of 2 tubeside passes per shell pass (I,J or G shells), when the 
 flow is two phase on the tubeside. [CURV 3802] $$
$M037
 *** WARNING *** I and J shells are calculated assuming equal duty in each
 half. This assumption can be inaccurate for I and J shells with only one
 tubeside pass. $NL 
 You can check this assumption by modelling each half of the I or J shell
 separately as an E shell, in Simulation mode. The calculated tubeside exit 
 conditions from first E shell give the inlet conditions to the second.
 (The first E shell is the one with the tubeside inlet: the shell length is
 half that of the I or J shell.)
 The heat loads calculated for each half can then be compared. [CURV 3701] $$
$M038
 ** FATAL ERROR ** TASC3 can only perform calculations for RODbaffled 
 exchangers with single phase flow on the shellside, since appropriate two phase
 correlations are not available. [CURV 3603] $$
$M039
 *** WARNING *** The correlations for RODbaffles have been supplied by Phillips
 Petroleum Company to enable users to design or check exchangers with
 RODbaffles. However, the use of the correlations does not grant any licence
 under any Phillips patent. [CURV 3503] $$
$M040
 ** FATAL ERROR ** $ST $SI The exchanger is operated as a falling film 
 evaporater, but the film side is single phase between the inlet and outlet 
 temperatures at the system pressure. Please check the data. The most likely 
 cause is missing the bubble point in isothermal or nearly isothermal cases. 
 If this is the case amend the temperatures or system pressure so that phase 
 change takes place. [CURV 2805] $$
$M041
 *** WARNING *** The exchanger is operated as a falling film evaporater, with 
 the hot stream condensing. However, in the geometry data, the exchanger has 
 been specified as countercurrent (input item 103.4), which implies that the 
 hot stream is condensing in upflow. The methods are suspect in this 
 situation. Please check whether the exchanger should be co-current. 
 [CURV 1908] $$

$M050
 ** FATAL ERROR ** The thermosyphon stream (stream 2, the cold stream) must
 be two phase.  Its T-h-x data must have x (quality, vapour mass fraction) 
 which is not all =0 (liquid only) or all =1.0 (vapour only).
$M051
 *** WARNING *** You did not specify a pressure at the liquid surface (in the
 distillation column or equivalent) for this thermosyphon stream. A value of 
 $R1 has been estimated from the exchanger inlet pressure ($R2) you specified.
 The difference is based on the gravitational head in the inlet line, assuming
 negligible frictional losses there. When the thermosyphon stream flowrate
 comes to be calculated, the exchanger inlet pressure will be modified to 
 allow for such losses.
$M052
 *** WARNING *** Based on the pressure of $R1 at the liquid surface in the
 column, and an initial estimate of $R2 at inlet to the exchanger, the
 corresponding temperature and quality (vapour mass fraction) at inlet
 have been calculated to be $R3 and $R4.  Your data input for one or both
 of these was different.  The temperature has been reset to the calculated 
 value, and the quality set to zero.
$M053
 *** WARNING *** You did not specify pressure dependence for the properties
 of the thermosyphon stream (stream 2). This may lead to inconsistencies,
 or inaccurate results.  Switch pressure dependence on, or if possible, supply  
 properties data at a second pressure level. $NL
 The estimated exchanger inlet pressure is currently $R1, while the outlet
 pressure must be above $R2, the pressure in the column. All your property
 data will be calculated at a pressure of $R3, where the bubble point is
 $R4.
 
$M100
 *** WARNING *** TASC has failed to calculate a tubecount. Your input value of
 $I1 will be used. $$
$M101
 *** WARNING *** TASC has failed to calculate a tubecount. Furthermore, the
 area occupied by the input number of tubes ($I1) of outside diameter $R1, is 
 greater than the area defined by the shell inside diameter ($R2), the bundle 
 to shell radial clearance ($R3), and the positions of the top and bottom rows 
 of the tube bundle. $NL 
 TASC by default calculates the positions of the top and bottom rows of the 
 tube bundle, but they can also be set in the input on line 109. [OUTP 1042] $$
$M102                  
 *** WARNING *** TASC has failed to calculate a tubecount, and you have not
 input a tubecount. A further attempt to set a tube count will be made. $$
$M103
 ** FATAL ERROR ** A single tube of outside diameter $R1 cannot fit into the
 E,I,J,K,D or M shell with an inside diameter of $R2 and bundle to shell radial 
 clearance of $R3. Please check your input geometry carefully. $$
$M104
 ** FATAL ERROR ** Two tubes of outside diameter $R1 and pitch $R2 cannot 
 fit into the F or G shell with an inside diameter of $R3 and bundle to shell 
 radial clearance of $R4. Please check your input geometry carefully. $$
$M105
 ** FATAL ERROR ** Dividing the area defined by the shell inside diameter ($R1)
 and the bundle to shell radial clearance ($R2), by the area occupied by a
 single tube with a pitch of $R3, gives a simple tubecount of $I1 for a full
 bundle. However, this is less than the number of tubeside passes, $I2. Please 
 check your input geometry carefully. $$ 
$M106
 *** WARNING *** Dividing the area defined by the shell inside diameter ($R1)
 and the bundle to shell radial clearance ($R2), by the area occupied by a
 single tube with a pitch of $R3, gives a simple tubecount of $I1 for a full
 bundle. This value is used by TASC, but you are advised to check your input 
 geometry carefully. If you did not enter a tubecount on line 106, or the
 positions of the top and bottom rows of the tube bundle on line 109, then
 please consider doing so.$$
$M107
 *** WARNING *** TASC has calculated a tubecount of $I1, which is less than the
 tubecount of $I2 which you input. Your input value will be used. [OUTP 1013] $$
$M108
 *** WARNING *** The area occupied by the input number of tubes ($I1) of 
 outside diameter $R1, is greater than the area defined by the shell inside 
 diameter ($R2), the bundle to shell radial clearance ($R3), and the positions 
 of the top and bottom rows of the tube bundle. However, TASC has calculated 
 a tubecount of $I2 which will be used. $NL
 TASC by default calculates the positions of the top and bottom rows of the 
 tube bundle, but they can also be set in the input on line 109. [OUTP 1042] $$
$M110
 *** WARNING *** The checking or simulation calculation has terminated
 after $I1 iterations, because of excessive pressure drop on the $SI. $NL
 The stream pressure has not been allowed to fall below 10% of the inlet 
 pressure. The calculated pressure loss may be implausibly high, which
 suggests that there is likely to be choked flow on the $SI.
$M111
 *** WARNING *** The checking or simulation calculation has terminated
 after $I1 iterations, because of a temperature cross.
$M112
 *** WARNING *** The checking or simulation calculation has terminated
 after $I1 iterations, because of choking: See separate message.
$M113
 *** WARNING *** The checking or simulation calculation has not converged
 after $I1 iterations, which is the maximum permitted number.

$M201
 ** WARNING ** Vapour belts are not permitted for shellside outlet or
 intermediate nozzles, or on X-shells.  TASC will assume that the 
 shellside nozzle type is plain. 
$M202
 ** WARNING ** The shellside inlet nozzle orientation is $I1 degrees and the
 tubeside inlet nozzle orientation is $I2 degrees. These have been either
 worked out by TASC on the basis of the hot stream inlet nozzle at the top 
 (0 degrees) and cold stream inlet nozzle at the bottom (180 degrees), or 
 they have been specified in the input data. However, the orientation of 
 the inlet nozzles is inconsistent with the countercurrent to first tubeside 
 pass flag. You should either change the countercurrent to first tubeside 
 pass flag or change/specify the orientation of the nozzles.
$M203
 ** WARNING ** $SI $ST : The inlet and outlet nozzle are offset by ninety
 degrees.  TASC does not yet make full allowance for such cases.
$M204
 ** WARNING ** $SI $ST : The outlet nozzle in F, G, H, OR X shells must be
 on the opposite side from the inlet nozzle, and has been reset accordingly.
$M205
 ** FATAL ERROR ** $SI Nozzles:  You have either not specified any 
 nozzles when they are needed, or have specified one of the types of 
 nozzle more than once, or you have not specified an inlet nozzle.  
 Your input data cannot be interpreted.
 Please check that you specify one of the following combinations: $NL
 Inlet and outlet nozzle $NL
 Inlet and outlet and intermediate nozzle (multiple shells in series) $NL
 Inlet and liquid-only outlet and vapour-only outlet (mandatory on
 the shellside of K-shells, not allowed for multiple shells in series, 
 or on the shellside of X-shells)
$M206
 ** WARNING ** $SI Nozzles:  You should specify either inlet and outlet 
 nozzles, or inlet, liquid-only-outlet and vapour-only-outlet nozzles.  
 [Liq/vap-only nozzles are mandatory on the shellside of kettles, but 
 are not allowed for the shellside of X-shells, or for thermosyphon 
 streams].  You have not specified a permissible set of nozzles.
 TASC will try to interpret your input data, but you should
 check carefully the nozzle information in the program output.
$M207
 ** WARNING ** $SI Nozzles:  For multiple shells in series, you 
 should specify inlet, outlet and intermediate nozzles. Your nozzle 
 input is different. TASC will try to interpret it, but you should 
 check carefully the nozzle information in the program output.
$M208
 ** FATAL ERROR ** $SI Nozzles:  TASC has tried to interpret your
 input data and failed.
$M209
 ** WARNING ** $SI Nozzles: For I or J shells, TASC3 sometimes 
 adjusts the nozzle diameters by a factor of 0.707 (check the TASC3
 output). However, TASC4 does not adjust the specified nozzle 
 diameters. Please check if your data set is from TASC3, and adjust 
 your nozzle diameters if necessary. 

$M210
 ** WARNING ** The Thermosyphon stream flow has been reduced from an 
 initial estimate of $R1 down to $R2, in order to reduce the pressure
 loss in the inlet line, and ensure that the pressure at the exchanger
 inlet is above that at the liquid surface in the column.
 $NL The flowrate of the hot stream has been reduced correspondly, to 
 maintain a heat balance.
$M211
 ** WARNING ** The heat transfer calculation has not converged for the
 current thermosyphon flowrates. (shellside = $R1, tubeside = $R2).
 The ratio of actual to required area is $R3.
$M212
 ** FATAL ERROR ** The calculation of thermosyphon flowrate has failed 
 to converge. For the current estimate of flowrate, $R1, the pressure
 loss in the exchanger and inlet/outlet lines is $R2, while the driving 
 head due to gravity is $R3.  Check other messages, and specification of
 exchanger and inlet/outlet lines. Use a new estimate of flowrate, and 
 try again.
$M213
 ** WARNING ** The thermosyphon calculation has been aborted because of
 the above fatal error.  Thermosyphon flow iteration $I1, heat balance 
 iteration $I2.

$M220
 *** WARNING *** The tube length increment has been specified as $R1, 
 but this is unacceptable, so TASC uses a default tube length increment  
 of $R2. The specified tube length increment is unacceptable because it
 is either negative, or it is zero but the specified maximum and 
 minimum tube lengths are not equal, or it is greater than the 
 difference between the specified maximum and minimum tube lengths.
$M221
 *** WARNING *** You have specified the number of baffles as zero. 
 The exchanger has been re-defined as unbaffled, and the baffle type reset
 accordingly.  Input relating to baffles will be ignored.
$M222
 *** WARNING *** The number of baffles specified $I1 is inconsistent with the
 shell type. Expected numbers could be $I2 or $I3. $NL
 G, I and J-shells have an odd number (includes baffle under cental nozzle).
 $NL H-shells have an even number. (for H shells only, the number of baffles
 has been reduced by one).
$M223
 *** WARNING *** The number of baffles specified $I1 is inconsistent with the
 nozzle orientations, and up and over flow. The expected numbers could be
 $I2 or $I3. $NL
 For each shellside flow path, there is an odd number of baffles if inlet 
 and outlet nozzles are on the same side, or an even number if they are on
 opposite sides.  F, G and H shells always have nozzles on opposite sides .$NL
 E, F-shells have one shellside flow path, G,I and J two paths, H-shells four.
 G, I and J-shells are assumed to have an additional baffle under the central 
 nozzle. H-shells have two such additional baffles.
$M224
 *** WARNING *** A calculated endspace length was below zero. The endspace
 is the endlength, $R1, minus the tubeplate thickness (plus projection
 if any) $R2.  The endspace has been set to $R3, and the endlength adjusted
 to $R4. (for U-tubes, tubeplate and endspace lengths can be near zero)
$M225
 *** WARNING *** The length of the baffled region, $R1, plus the endlengths,
 were inconsistent with the tubelength $R2.  The endlengths have been
 reset to $R3 and $R4.  $NL
 Check Help text for exact definitions of endlengths.  
$M226
 *** WARNING *** The length of the baffled region, $R1, plus the endlengths,
 were greater than the tubelength $R2.  The number of baffles has been
 reset from $I1 to $I2, and the endlengths reset to $R3 and $R4.  $NL
 Check Help text for exact definitions of endlengths.  
$M227
 *** WARNING *** A shellside nozzle diameter $R1 is larger than $R2, the
 corresponding endspace length (or than twice the baffle pitch for central 
 nozzles). The corresponding endlength and tubeplate thickness are $R3 and $R4.
$NL  Check your input carefully.
$M228
 *** WARNING *** An endspace length $R1 is less than the baffle pitch $R2,
 and/or the TEMA minimum (2 inches/ 50mm).
 The corresponding endlength and tubeplate thickness are $R3 and $R4.
 Check your input carefully. 
$M229
 *** WARNING *** The number of baffles, $I1, as specified or revised, is 
 inconsistent with the minimum for the shell type. 
 (2 for E and F , 5 for G, I and J, and 6 for H-shells: a baffle is assumed
 under a central nozzle). 
 The exchanger has been re-defined as unbaffled, and the baffle type reset
 accordingly.
$M230
 *** WARNING *** You did not specify the number of baffles. This has been
 calculated as $I1, the nearest value, given the tube length $R1, endlengths 
 $R2 and $R3, (as input or estimated) and a baffle pitch of $R4. $NL
 Note: for G, H, I and J shells, with central nozzles, there is assumed to be
 a baffle under such a nozzle.
$M231
 *** WARNING *** There is a full support baffle (blanking baffle) present
 (specified or default for S and T type rear heads), but the distance 
 beyond this baffle has not been specified. The distance beyond the 
 blanking baffle has been calculated as $R1. For U-bends, this distance is
 the estimated support plate thickness $R2. For S-type rear heads, the
 distance is two tubeplate thicknesses ($R3) plus the greater of 100mm or
 the estimated support plate thickness. For all other rear head types, the
 calculated distance beyond the blanking baffle is the tubeplate thickness 
 plus the greater of 100mm or the estimated support plate thickness. 

$M240
 *** WARNING *** A specified shell to nearest tube row distance $R1 is less 
 than the shell to bundle radial clearance $R2 plus half the tube outside 
 diameter $R3. This is not possible so TASC will calculate this distance.
$M241
 *** WARNING *** The sum of the two specified distances from the shell to 
 the extreme tube row centrelines, $R1 plus $R2, is greater than the shell
 inside diameter $R3.
 This is not possible so TASC will calculate these two distances.

$M300
 *** WARNING ***  TASC has failed to calculate the interpass tubeside 
 enthalpy accurately. 
 $NL
 The tubeside enthalpy at the end of pass 1 or 3 is $R1, but the mean of 
 the enthalpies at the end of this pass, and the beginning of the next 
 pass, is $R2. The difference between the enthalpy at the end of the pass 
 and the mean, compared to the heat load, is $R3 %. 
 $NL
 TASC continues assuming that the interpass enthalpies have the mean value.


$M501
 *** ERROR *** $NL
 REASON: The iterations for the local heat transfer rate failed to converge
  to the normal accuracy.  Successive values of the local overall heat
 transfer were $R1 and $R2. 
$NL $NL
 PROGRAM ACTION: Calculation may be suspended. 
$NL $NL
 USER ACTION: Treat results with caution. Contact HTFS if program halted.
$M502
 *** ERROR *** $NL
 REASON: The iterations for the local tubeside boiling heat transfer coefficient
 failed to converge to the normal accuracy.  Successive heat fluxes were $R1 and
 $R2.
 $NL $NL
 PROGRAM ACTION: Calculation may be suspended.
 $NL $NL
 USER ACTION: Treat results with caution. Contact HTFS if program halted.
$M503
 *** WARNING *** $NL
 REASON: The critical heat flux was exceeded in the calculation at qualities
 between $R3 and $R4.  At the point with a quality of $R3 the calculated
 heat flux was $R1 and the critical heat flux was $R2.
 $NL $NL
 PROGRAM ACTION: Calculation continued using the calculated heat flux OR
 if you have requested a post-dryout heat transfer calculation, the program
 limits the calculated heat flux to the critical heat flux. 
$NL $NL
 USER ACTION: You should consider revising the design or the process 
 conditions.  

$M504
 *** WARNING *** $NL
 REASON: Boiling calculation - mixture correction parameter $R1 is greater
 than the maximum allowable value of $R2.
$NL $NL 
 PROGRAM ACTION: Parameter set to 1.0 and calculation continued.
$NL $NL 
 USER ACTION: Check data and treat results with caution.
$M505
 *** WARNING *** $NL
 REASON: Boiling calculation - mixture correction factor of $R1 is greater 
 than maximum allowable value of $R2.
$NL $NL 
 PROGRAM ACTION: Correction factor set to 1.0 and calculation continued.
$NL $NL 
 USER ACTION: Check data and treat results with caution.
$M506
 *** WARNING *** $NL
 REASON: Boiling calculation - mixture correction factor of $R1 is less  
 than minimum allowable value of $R2.
$NL $NL 
 PROGRAM ACTION: Correction factor set to $R2 and calculation continued.
$NL $NL 
 USER ACTION: Check data and treat results with caution.
$M507
 *** WARNING ** $NL
 REASON: Parameter in critical heat flux correlation for shellside boiling
 out of normal range.
$NL $NL 
 PROGRAM ACTION: Calculation continued.
$NL $NL 
 USER ACTION: Check data and treat results with caution.
$M508
 *** WARNING *** $NL
 REASON: Horizontal shell with axial flow boiling - insufficient liquid in 
 the bottom of the shell to cover the tubes
$NL $NL 
 PROGRAM ACTION: Local heat transfer rate set to zero.
$NL $NL 
 USER ACTION: Check data and treat results with caution.
$M509
 *** WARNING *** $NL
 REASON: The calculated value of Xtt of $R1 was out of range of validity 
 ($R2 to $R3) of the shellside two-phase flow pattern map.
$NL $NL 
 PROGRAM ACTION: Calculation continued.
$NL $NL 
 USER ACTION: Check data and treat results with caution.
$M510
 *** WARNING *** $NL
 REASON: The calculated value of the superficial velocity of $R1 was out of
 range of validity ($R2 to $R3) of the shellside two-phase flow pattern map.
$NL $NL 
 PROGRAM ACTION: Calculation continued.
$NL $NL 
 USER ACTION: Check data and treat results with caution.
$M511
 *** WARNING *** $NL
 REASON: The shellside two phase flow pattern map predicted intermittent flow.
 $NL $NL
 PROGRAM ACTION: Calculation continued.
 $NL $NL
 USER ACTION: Assess consequences of intermittent flow
$M512
 *** WARNING *** $NL
 REASON: Tubeside boiling - the calculated critical heat flux of $R1 was 
 abnormal (data out of range of correlation)
$NL $NL 
 PROGRAM ACTION: Calculation continued.
$NL $NL 
 USER ACTION: Check data and treat results with caution.
$M513
 *** ERROR *** $NL
 REASON: Incorrect input to subroutine htsing for single phase heat transfer 
 inside tubes.
$NL $NL 
 PROGRAM ACTION: Calculation halted.
$NL $NL 
 USER ACTION: Check data. Inform HTFS if error persists.
$M514
 *** WARNING *** $NL
 REASON: Rayleigh number of $R1 outside range of validity ($R2 to $R3) of 
 correction to laminar Nusselt number for effects of free convection on 
 heat transfer in vertical heated downflow or cooled upflow.
$NL $NL
 PROGRAM ACTION: Calculation continued.
$NL $NL 
 USER ACTION: Check data and treat results with caution.  See HTFS Handbook
 Sheet SM2.
$M515
*** WARNING *** $NL
 REASON: Failure to converge natural convection calculation for single
 phase heat transfer inside tubes.  There is a possibility of instability.
$NL $NL
 PROGRAM ACTION: Calculation continued using result from last iteration.
$NL $NL
 USER ACTION: Check data and treat results with caution. 
$M516
 *** ERROR ***  $NL
 REASON: The iterations for the local shellside boiling heat transfer 
 coefficient failed to converge to the normal accuracy.  Successive heat
 fluxes were $R1 and $R2.
$NL  $NL
 PROGRAM ACTION: Calculation may be suspended.
$NL  $NL
 USER ACTION: Treat results with caution. Contact HTFS if program halted.
$M517
 *** WARNING *** $NL
 REASON: The crossflow flow distribution failed to converge within 1 per cent,
 but was within 10 percent
$NL $NL
 PROGRAM ACTION: Calculation continued.
$NL $NL
 USER ACTION: Treat results with caution.
$M518
 *** ERROR *** $NL
 REASON: The crossflow flow distribution failed to converge within 10 per cent.
 $NL
 PROGRAM ACTION: Calculation normally halted.
$NL $NL
 USER ACTION: Check data.  Inform HTFS if error persists.
$M519
 *** WARNING *** $NL
 REASON: Mass transfer correction factor of $R1 in condensation calculations 
 out of normal range ($R2 to $R3).
$NL $NL
 PROGRAM ACTION: Mass transfer correction factor set to 1.0 and calculation 
 continued.
$NL $NL
 USER ACTION: Check data. Treat results with caution.
$M520
 *** WARNING *** $NL
 REASON: Liquid/vapour density ratio of $R1 in critical heat flux correlation 
  for tubeside boiling out of normal range ($R2 to $R3).
$NL $NL
 PROGRAM ACTION: Calculation continued using actual density ratio.
$NL $NL
 USER ACTION: Check data and treat results with caution. 
$M521
 *** WARNING *** $NL
 REASON: The correlations for single phase heat transfer and pressure loss
 in low-finned tubes were applied outside their range of validity.
$NL $NL
 PROGRAM ACTION: Calculation continued.
$NL $NL
 USER ACTION: Check data and treat results with caution. 
$M522
 *** WARNING *** $NL
 REASON: A parameter with value $R1 in the correlation for single phase 
 heat transfer and pressure loss in Rod Baffled exchangers was 
 outside its range of validity of $R2 to $R3.
$NL $NL
 PROGRAM ACTION: Calculation continued.
$NL $NL
 USER ACTION: Check data and treat results with caution. 
$M523
 *** WARNING *** $NL
 REASON: A simplified method was used for pool boiling heat transfer on low
  finned tubes because the critical pressure was not available.
$NL $NL
 PROGRAM ACTION: Calculation continued.
$NL $NL
 USER ACTION: Note that predictions may be over-conservative.
$M524
 *** FATAL ERROR *** $NL
 REASON: Error from PPP package.  Liquid properties returned, since vapour
  properties could not be found.
$NL $NL
 PROGRAM ACTION: Calculation normally halted.
$NL $NL
 USER ACTION: Check data.  Inform HTFS if error persists.
$M525
 *** FATAL ERROR *** $NL
 REASON: Error from PPP package.  Vapour properties returned, since liquid
  properties could not be found.
$NL $NL
 PROGRAM ACTION: Calculation normally halted.
$NL $NL
 USER ACTION: Check data.  Inform HTFS if error persists.
$M526
 *** WARNING *** $NL
 REASON: The method for the effects of natural convection on the
 single-phase heat transfer coefficient produced over-conservative results. 
$NL $NL
 PROGRAM ACTION: Calculated heat transfer coefficient of $R1 replaced by
 estimated minimum value of $R2.
$NL $NL
 USER ACTION: No action required, but you should check the property data. 

$M531 
 *** WARNING *** $NL 
 REASON: The tubeside critical heat flux could not be 
 calculated between qualities of $R1 and $R2, probably because the 
 program has predicted fully stratified flow in a horizontal tube. 
 $NL $NL
 PROGRAM ACTION: It was therefore not possible to do a calculation of
 post-dryout heat transfer (if requested) at these conditions, and the $NL 
 program has used the normal boiling heat transfer coefficient. 
 $NL $NL
 USER ACTION:  Note that the program has predicted fully stratified flow
 in a horizontal tube.  It may be desirable to increase the tubeside
 mass flux.

$M600
 **** THERMOSYPHON STABILITY ASSESSMENT ****
$NL  
 RESULT: Analysis using HTFS Handbook Sheet TM16 (1983) could NOT be performed.
$NL $NL
 PROGRAM ACTION: Stability condition of system not calculated.
$NL $NL                                                           
 USER ACTION: Check data and treat results with caution.
$NL $NL
 REFERENCE: HTFS Documents TM16, TP7, DR1, DR17 & Windows Help Text.
$$
$M601
 **** THERMOSYPHON STABILITY ASSESSMENT ****                         
$NL  
 RESULT: Analysis indicates that the system is likely to be stable.
$NL $NL
 DETAILS: The calculated stability point (HTFS Handbook TM16, 1983) is $NL
 $SI $SI $SI $SI $SI $SI $SI Figure = $I1 $NL
 $SI $SI $SI $SI $SI $SI $SI X3  = $R1    $NL
 $SI $SI $SI $SI $SI $SI $SI 'y' = $R2   ('y' = Rp1, or DP13F/DP01FA) $NL
 $SI $SI $SI $SI $SI $SI $SI 'z' = $R3   ('z' = Ja , or Rp2, or DP13A/DP13F)
 $NL $NL
 If you have the HTFS Handbook or Design Reports, see Handbook Sheets
 TM16, TP7, Design Report DR1, DR17 for information on the methods used.
$$ 
$M602
 **** THERMOSYPHON STABILITY ASSESSMENT ****
$NL  
 RESULT: Analysis indicates that two-phase instability 
 may result in the system.
$NL $NL
 DETAILS: The calculated value of the 'Exit Quality Number', X3 = $R1,
 which is greater than the stable value of 15.0
$NL $NL
 The calculated heat transfer and pressure drop do not allow for this
 instability. $NL
 You can usually reduce the exit quality, and hence the exit quality number,
 by reducing the flow resistance in the circuit, or increasing the driving 
 head of liquid. $NL
 See Windows Help text on Stability for more information.  $NL 
 If you have the HTFS Handbook or Design Reports, see Handbook Sheets
 TM16, TP7, Design Report DR1, DR17 for information on the methods used.
$$
$M603
 **** THERMOSYPHON STABILITY ASSESSMENT ****
$NL  
 RESULT: Analysis indicates that Excursive (Ledinegg) two-phase instability 
 may result in the system.
$NL $NL
 DETAILS: Calculated stability point in HTFS Handbook Sheet TM16 (1983) =  $NL
 $SI $SI $SI $SI $SI $SI $SI Figure = $I1 $NL
 $SI $SI $SI $SI $SI $SI $SI X3  = $R1    $NL
 $SI $SI $SI $SI $SI $SI $SI 'y' = $R2   ('y' = Rp1, or DP13F/DP01FA) $NL
 $SI $SI $SI $SI $SI $SI $SI 'z' = $R3   ('z' = Ja , or Rp2, or DP13A/DP13F)
$NL $NL
 The calculated heat transfer and pressure drop do not allow for this
 instability. $NL
 See Windows Help text on Stability for more information.  $NL 
 If you have the HTFS Handbook or Design Reports, see Handbook Sheets
 TM16, TP7, Design Report DR1, DR17 for information on the methods used.
$$
$M604
 **** THERMOSYPHON STABILITY ASSESSMENT ****
$NL  
 RESULT: Analysis indicates that Oscillatory (Density Wave) two-phase $NL
 instability may result in the system.
$NL $NL
 DETAILS: Calculated stability point in HTFS Handbook Sheet TM16 (1983) =  $NL
 $SI $SI $SI $SI $SI $SI $SI Figure = $I1 $NL
 $SI $SI $SI $SI $SI $SI $SI X3  = $R1    $NL
 $SI $SI $SI $SI $SI $SI $SI 'y' = $R2   ('y' = Rp1, or DP13F/DP01FA) $NL
 $SI $SI $SI $SI $SI $SI $SI 'z' = $R3   ('z' = Ja , or Rp2, or DP13A/DP13F)
$NL $NL
 The calculated heat transfer and pressure drop do not allow for this
 instability. $NL
 See Windows Help text on Stability for more information.  $NL 
 If you have the HTFS Handbook or Design Reports, see Handbook Sheets
 TM16, TP7, Design Report DR1, DR17 for information on the methods used.
$$
$M605
 **** THERMOSYPHON STABILITY ASSESSMENT ****                         
$NL  
 Analysis indicates that the system is likely to be stable. $NL
 The Overall Pressure Ratio, Rp = $R1, which is less than the critical value 
 of 2.0   
$NL $NL
 See Windows Help text on Stability for more information.  $NL 
 If you have the HTFS Handbook or Design Reports, see Handbook Sheet
 TM16, TP7, Design Report DR1, DR17 for information on the methods used.
$$
$M606
 *** WARNING *** The thermosyphon operating point was beyond the range of the 
 two-phase stability correlations [ If you have the HTFS Handbook, see Sheet
 TM16, Figure $I1. Use the details above to see how far beyond the range it is]
$NL The stability calculation used the limit value on the Figure.
$$
$M620
 **** VIBRATION ANALYSIS MESSAGES ****                         
$NL  
The vibration analysis has generated $I1 warning/information message/s. $NL
Details are printed at the end of the lineprinter output file.
$$
